presentation one world trade center

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The rising: a look back at the construction of one world trade center.

It has been a journey filled with deep emotion and pride as the tallest building in the Western Hemisphere took shape and form.

Restoring the skyline

One World Trade Center looms over the wedge-shaped pavilion entrance of the National September 11 Museum, lower right, and the square outlines of the memorial waterfalls in New York on Sept. 5, 2013. The 1,776-foot-high building stands as a symbol of resilience in the wake of 2001's Sept. 11 terror attacks.

Setting the scene

Construction gets under way at the World Trade Center site and the One World Trade Center tower on Sept. 2, 2010.

Hard at work

Construction cranes work above the rising structure of New York's One World Trade Center on Jan. 5, 2011. The top deck is 613 feet (187 meters) above street level in this photo, and the steel columns were in place to support the 54th floor.

People walk past the construction site of the World Trade Center in New York on Sept. 9, 2011.

Twin towers of light

The Tribute in Light shines brightly next to the Statue of Liberty and One World Trade Center, left, on Sept. 10, 2012, to commemorate the 11th anniversary of the Sept. 11 attacks.

In memoriam

The construction of One World Trade Center, up to 104 floors, is seenon Sept. 11, 2012, across the Hudson River at Liberty State Park in Jersey City, N.J. A runner glides his hand along the wall of "Empty Sky," New Jersey's memorial to the 749 people from the state who died during the Sept. 11 terrorist attacks on the World Trade Center.

The final section of the spire that will top One World Trade Center is raised past iron workers to the top of the building in New York on May 2, 2013.

Top of the world

The final piece of the One World Trade Center spire is attached to the building by ironworkers in New York on May 10, 2013. The spire raised the building to its full height of 1,776 feet, making it the tallest building in the Western Hemisphere.

What a view!

Ironworker Tyler Brown leans on a safety fence to look at the New York skyline after watching a crane lift the final piece of the spire to the top of the One World Trade Center on May 10, 2013.

Tourist attraction

People line up to look into the South Pool underneath the One World Trade Center tower at the National September 11 Memorial in New York on Aug. 29, 2013.

Rising high

A woman flies a kite in front of the skyline of New York's Lower Manhattan and One World Trade Center in a park along the Hudson River in Hoboken, N.J., on Sept. 3, 2013.

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The Untold Story of New York’s One World Trade Center

By Nadja Sayej

When photographer Joe Woolhead first heard about the September 11 attacks, he rushed to downtown Manhattan with his camera. He photographed a cloud of smoke emerging from the Twin Towers while riding on a moving subway car, which was crossing a bridge before it zipped back underground. Over the next decade, he took over two million photographs of the site, from rubble to construction, and endearing portraits of the construction workers who built the One World Trade Center, which opened in 2014. Today it remains a symbol of strength, resilience, and hope.

Now a new book traces the photos and story that saw the tragedies unfold, leading up to the construction of the iconic building. Once More To The Sky: The Rebuilding of the World Trade Center is both a photo book and historical document that traces the path to building the One World Trade Center after 10 years of construction from 2005 to 2015. It released on August 31, coinciding with the 20th anniversary of the September 11 attacks.

Construction workers moving debris from the original World Trade Centers following the 9/11 attacks.

The $4 billion construction project was intimately documented by writer Scott Raab, who wrote a ten-part series for Esquire starting in 2005, and Woolhead, who became the official photographer for the World Trade Center to document its historic creation.

The book features never-before-seen photos of the skyscraper’s construction alongside portraits of engineers, boardroom meetings, and blueprints. It shows the growth of the epic project, starting from one of the first photos in the book, which depicts a dystopian cloud of smoke over piles of rubble, calling to mind an image from the Second World War.

“I was working at an unconscious level as I went day to day documenting the work that was going on,” Woolhead says. “I only really began to delve into the significance of the photos after a number of years had passed, and I realized there was a bigger picture I was capturing.”

The Statue of Liberty at night with the Tribute in Light—two beams of light symbolizing the fallen towers—in the background.

The book also features stories of people who helped build the building, as well as survivors and families of those who did not survive. “It has been a long, strange journey since 9/11,” Woolhead says. “Since I was involved with construction on a ground level, there were many delays, but it’s great to see the masterplan come together. I didn’t realize it would take so long.”

Construction begins on the new One World Trade Center, a skyscraper that would symbolically stretch to a height of 1,776 feet.

There are many intimate portraits of the workers who built the building ground up, and the book offers insight into their day-to-day work. “Being with the workers day in and day out, I felt like one of the crew,” Woolhead says. “It was great to document the work and they really appreciated it. They knew in the long run I was concentrating on the big picture, how the building was being built, and their work was going to be reflected in the photos I captured.”

By Charlotte Collins

By Joyce Chen

By Michelle Duncan

The book also covers the untold story of the tower, its controversies, and delays. “So much was going on behind the scenes,” Raab says. “It’s not just about rebuilding the World Trade Center, but rebuilding anything of this magnitude, it’s negotiating a certain amount of political uncertainty. It’s why everything has taken so long.”

An aerial view of One World Trade Center (home to Condé Nast, the parent company of Architectural Digest ).

It’s part-reportage, part photo book. In its essence, it’s a story of hope. “Now, more than ever, there are moments in a country’s history that you feel turning points—or hope there may be a turning point,” Raab says. “But that only becomes reality if enough people pull together. It enables people to come back down to work and live.”

The book resonates with today too. “We’re seeing this with the pandemic, it’s uncertain, but how will it look, looking back?” he adds. “A communal, national effort to address something that feels like 9/11. It threatens us to the very heart of our national soul.”

By Katherine McLaughlin

By Michael Gioia

• Getting Here
• Office Buildings
• 2 World Trade Center
• 3 World Trade Center
• 4 World Trade Center
• 7 World Trade Center
• THINGS TO DO

WORLD TRADE CENTER TIMELINE OF HISTORY

To become iconic is to transcend history itself. Discover the storied past of Downtown Manhattan and the World Trade Center…and what lies ahead, as this extraordinary place steps boldly into the future.

The TV home of the Mets, Jets and all things New York sports, has moved in and will begin broadcasting from a new set of studios at 4 World Trade Center on Saturday March 4.

Spotify signs lease to move their headquarters to the World Trade Center! The global digital music and video streaming service has leased floors 62-72 at 4 World Trade Center.

Brandon Maxwell (who styled Lady Gaga at the Superbowl) displayed his Fall/Winter collection at an exclusive fashion show at the World Trade Center. The show took place on the 71st floor of 4 World Trade Center and featured Bella Hadid, Joan Smalls, and Jourdan Dunn.

Cooling towers are now installed on the roof of 3 World Trade Center.

Legendary sports icon and human rights advocate, Billie Jean King gathered leaders across sectors to elevate the conversation on inclusive leadership at the third annual Billie Jean King Leadership Initiative at the WTC events space.

Larry Silverstein celebrates the steel topping out of 3 WTC with 500 union construction workers.

Scheduled to open in 2020, the Perelman Performing Arts Center will serve as a vital cultural hub bringing three flexible performance venues and community programming to Lower Manhattan.

Global Atlantic Financial Group has signed a deal for the whole 51st floor of the 2.3-million-square-foot 4 World Trade Center.

The World Trade Center retail mall is now open! More than 100 stores officially opened to the public today - marking another great milestone at the new World Trade Center.

Eataly opens a 48,000 square foot food emporium on the 3rd floor at 4 World Trade Center

Validus, a Bermuda-based insurance firm, has signed a deal to relocate its Big Apple operations to 4 WTC from within Downtown. The company has signed a 16-year lease for 24,489 square feet.

Silverstein Properties Chairman Larry Silverstein announced today that the company has signed a 16-year lease with Zurich American Insurance Company, the leading multi-line insurance provider, for 132,000 square feet of office space at 4 World Trade Center.

World Trade Center’s one-acre Liberty Park opens to the public .

The final concrete bucket, which was adorned with the same American flag that was used at the topping out of 7 and 4 WTC, was signed by Larry Silverstein, construction workers, and the assembled New York dignitaries. It was then raised 1,079 feet in the air and placed at the top of the 80-story tower.

Hudson River Trading, which uses mathematical and statistical techniques to develop trading algorithms, has signed a 69,000-square-foot lease for the 57th and 58th floors of the 2.3-million-square-foot tower, according to a press release from the landlord.

New York Commuters can now walk underground from Fulton Street to World Trade Center Transportation Hub

Morningstar Inc. has officially moved its credit-rating subsidiary into 4 World Trade Center.

“While I am disappointed that 21st Century Fox and News Corp have elected to hold off on moving their headquarters, I am immensely grateful to the Murdochs and their talented team, as well as to the Bjarke Ingels Group and our partners at the Port Authority, for their inspired work over the past year. “Make no mistake: it won’t be long before we find a great company to anchor 2 World Trade Center. Lower Manhattan has firmly established itself as the neighborhood of choice for the world’s most dynamic technology, advertising, media, financial and other creative businesses. Downtown’s momentum is palpable and unstoppable – more than 600 firms have moved to Downtown since 2005, leasing over 15 million square feet of space. We at Silverstein Properties remain 100 percent committed to successfully completing this historic rebuilding effort.” Larry Silverstein, Chairman, Silverstein Properties Inc.

The Silverstein Properties-developed building will stand 80 stories tall when finished and features 2.8 million square feet of space.

GroupM will expand an additional 170,000 square feet at 3 WTC, the tower being constructed by Silverstein Properties

ACWTC Chairman John Zuccotti and President/Director Maggie Boepple today announced the selection of the Brooklyn-based firm REX as the lead architect for The Performing Arts Center at the World Trade Center. Scheduled to open in 2019, PACWTC will serve as a major new addition to New York’s cultural landscape, producing and premiering works of theater, dance, music, musical theater, opera, and film, as well as productions that cross multiple disciplines.

Silverstein Properties announced today that it has signed a 17-year lease with SNY for 83,000 square feet of office and studio space at 4 World Trade Center.

Now fully leased, Westfield World Trade Center’s 365,000 square feet of retail space is equal to nine full city blocks. An additional 90,000 square feet will come online when Tower 2 opens.

"The two and a half floors that we’ll occupy in this brand new building will bring a lot of important features to MediaMath’s Global Headquarters— state of the art office systems, proximity to top publishers and advertisers, enough conference rooms to actually accommodate our team, dedicated classroom space, and some fun features like yoga rooms, communal areas and breathtaking views." Read more: http://blog.mediamath.com/blog/culture/what-the-move-to-4-world-trade-center-means-for-mediamath/

Two of Crain’s 50 fastest growing companies are 4 WTC tenants: Media Math (13) and Syntactex (12).

3WTC has just passed the halfway point in its rise. Once completed, the total between the towers will likely exceed 50,000 employees -- an anticipated influx that's already translating into an unprecedented retail boom. -New York YIMBY

PadillaCRT signed a 15-year deal yesterday for 14,639 square feet at the Downtown tower at the corner of Liberty Street and Trinity Place, Silverstein announced.

Headquartered in Charlotte, NC, Dixon Hughes Goodman LLP leased 5,023 square feet on the 44th floor for 7 years. The company was previously a tenant at Silver Suites at 7 WTC, along with Syntactx, which leased 6,930 square feet for 7 years, also on the 44th floor.

Syntactx, which leased 6,930 square feet for 7 years, also on the 44th floor.

Like eight other intersections, the crossroads was subsumed in 1967 into the 16-acre superblock on which the World Trade Center was built. Since Sept. 11, 2001, its four corners have been occupied by rescue workers, recovery workers or construction workers. The crossroads is to return to public use for the first time since ham-radio and hi-fi buffs swarmed the little appliance and electronics stores of Radio Row...

2 WTC is the capstone in the redevelopment of the World Trade Center and the final component of the revitalization of Lower Manhattan. The 80+ story building will serve as the new headquarters for 21st Century Fox and News Corp who will occupy the lower half of the tower, housing their subsidiary companies and more than 5,000 people under one roof.

Silverstein Properties, 21st Century Fox and News Corp have agreed to the basic terms of a 30-year lease that will encompass at least 1.3 million square feet of office space at 2 World Trade Center. The space, which would include newsrooms, TV studios and offices, is located on the lower half of the 2.8 million square foot tower. The term sheet, while nonbinding, indicates that the parties have agreed in principle to the major parameters of the lease.

The new Brookfield Place Shopping Center is open. Brookfield Properties national director of retail leasing Ed Hogan said it will provide a luxury shopping experience in the complex formerly known as the World Financial Center.

The new steel of 2015 arrives at 3 World Trade Center. Ironworkers pick the first beam from the truck and lift it onto the 7th floor deck of the building.

Nobu, for 20 years one of New York’s most storied and influential restaurants, is leaving its Tribeca home for 195 Broadway — in the heart of the Wall Street/World Trade Center area.

Silverstein Properties announced today that IEX, a start-up stock market dedicated to institutionalizing fairness through technology, and the subject of Michael Lewis’ book, Flash Boys, has signed a 7-year, 13,000 square foot (1,208 square meter) lease at 4 World Trade Center. The company expects to move to the 44th floor of 4 World Trade Center in April 2015.

The 65,000 square feet of commercial space at Fulton Center is fully leased, and tenants are expected to include beauty salons, drugstores, and grab-n-go eateries. The MTA anticipates that the shops will open in mid-2015.

This passageway links businesses and ferry service to the west of the trade center site to New Jersey-bound PATH trains and the rest of lower Manhattan to the east.

One World Trade Center sidewalks are open to the public for the first time in 13 years.

Silverstein Properties announced today that leading independent investment research provider Morningstar, Inc. has signed a 10-year, 30,000 square foot lease at 4 World Trade Center. The company expects to move to the 48th floor of 4 World Trade Center in mid-2015.

3 WTC in progress from Greenwich St. with the completed 4 WTC in the background blending with the clouds and the sky.

A crane lifts one of the 114 rafters to be installed on the WTC Transportation hub designed by Santiago Calatrava.

Silverstein Properties announced today that global technology company MediaMath has signed a 15-year, 106,000 square foot lease at 4 World Trade Center. The company will consolidate its more than 300 NY-based employees from three Midtown locations into the 44th, 45th, and 46th floors of 4 World Trade Center when it moves into the 72-story tower in early 2015.

Larry Silverstein and Janno Lieber of Silverstein Properties cut the ceremonial ribbon, along with Mayor Michael Bloomberg, 4 WTC Architect Fumihiko Maki, and other city officials.

“Sky Memory” is a delicate, 98-foot-diameter titanium arc by the sculptor Kozo Nishino, of Kyoto, Japan.

The last piece of the spire ascends to the top of One World Trade Center. The ironworker crew on top are Kevin Scally (foreman), John Collins (signalman), and connectors Mike O'Reilly, Ryan Gibbs, Tim Conby and James Brady.

Mayor Bloomberg chooses Christy Ferer, the Chief Executive Officer and Founder of Vidicom; Community Board 1 Chairperson Julie Menin; Silverstein Properties Chief Executive Office and President, Larry Silverstein; John Zuccotti, co-Chairperson of Brookfield Office Properties; and Zenia Mucha, Vice President of the Walt Disney Company. The P.A.C. board is tasked with fundraising and making collective decisions about the facility’s programming and expenses.

The agency will be combining its offices from 180 Wall Street, 2 Washington Street and 250 Church Street into the 2.3 million-square-foot tower to become the second government tenant in the building.

Silverstein Properties announces that MSCI Inc. signed a 20-year, 125,000 square-foot lease at 7 World Trade Center, bringing the first World Trade Center building to 100% occupancy. The successful leasing of the 52-story building just North of the World Trade Center site further proved Downtown’s commercial capability and residential resurgence in the decade following September 11, 2001.

President Obama, President Bush, Mayor Bloomberg, Larry Silverstein and Port Authority officials gathered with those who lost loved ones in the September 11, 2001 terrorist attacks on the World Trade Center site to mark both the 10 year Anniversary and for the dedication ceremony for the National September 11 Memorial and Museum.

Contrary to what many believed would happen, Lower Manhattan shifts into one of the fastest-growing residential areas of New York City. Downtown, the southern tip of Manhattan below Canal Street, the population has nearly doubled over the last decade, adding 26,800 residents.

The 9/11 Memorial Plaza opened on September 11, 2011, exactly ten years after the World Trade Center attacks. On August 15, 2011, the lights that illuminate the waterfalls were turned on for the first time.

The final steel beam was lifted 977 feet above ground and placed atop the 72 story skyscraper. The ceremony, hosted by Larry Silverstein and local elected officials, honored the 2.3 million-square-foot building set to open in Fall of 2013

Condé Nast finalized a $2 Billion deal with the Port Authority of New York and New Jersey to become the anchor tenant on One World Trade Center. The magazine empire, which will relocate from their headquarters at 4 Times Square to downtown, signed the 25-year lease agreement and will occupy up to 1 million square feet

Silverstein Properties announces that the steel has risen to the 23rd floor of 4 World Trade Center and that the foundation work for 2 and 3 World Trade Center is complete.

On April 5, 2011, Mayor Bloomberg joined William J. Perlstein, WilmerHale co-managing partner, and Larry A. Silverstein at the signing of WilmerHale’s 7 World Trade Center tenant lease, which is the first to incorporate groundbreaking language crafted by industry leaders working with the Mayor’s Office of Long-Term Planning and Sustainability to promote enhanced energy efficiency and sustainability.

Mayor Bloomberg’s office announces that the New York City government will lease 14 floors of 4 World Trade Center, marking the first tenant lease to be signed on the east side of the World Trade Center site.

Foundation work begins for World Trade Center Towers 2 and 3 marking the first time every part of the site is under construction.

The States of New York and New Jersey, the City of New York, the Port Authority and Silverstein Properties announced the outline of a development plan for the east side of the World Trade Center site. The plan calls for the immediate restoration of the east side of the WTC site to at least street level, the completion of Tower 4 by 2013, possible completion of Tower 3 by 2015, and the phase-in of Tower 2 over time. Other projects at the site, including the 9/11 Memorial, One World Trade Center, the WTC Transportation Hub and other public infrastructure, will continue moving forward. Negotiations were extended for 120 days for both sides to continue discussion and the new agreement is expected to be signed in the summer of 2010.

After a three-month long hearing, an arbitration panel ruled to give the Port Authority of New York and New Jersey and Silverstien Properites 45 days to come up with a new development schedule for the Towers 2, 3 and 4.

NCR is a world leader in consumer transaction technologies and with their products and services, more than 23 billion consumer self-service transactions processed globally.

Mansueto Ventures, who publish Inc and Fast Company, made their home at 7 WTC after being founded in 2005 and currently occupy the entire 29th floor.

Mayor Michael Bloomberg invited leaders including Assembly Speaker Sheldon Silver, New Jersey Governor Jon Corzine, Governor David Patterson, Silverstein Properties and Port Authority officials to Gracie Mansion to discuss the future of the site and ended with a promise of another meeting. This meeting marked another step forward in the rebuilding process of the WTC.

The Port Authority of New York and New Jersey announced that they wanted to cancel construction on Tower 5 altogether to cut the amount of office space available in the reconstructed World Trade Center to 5 million square feet.

The Port Authority of New York and New Jersey changed the name of the Freedom Tower to 1 World Trade Center with the rationale that this would make the building more marketable for tenants and the public.

Tower 4 was designed by Japanese architect Fumihiko Maki. Maki's minimalist vision for this 64-story tower complements Daniel Libeskind's master plan, which uses the four WTC towers as an abstract spiral descending towards the National 9/11 Memorial. At 975 feet, Tower 4 is the shortest of the east-side towers, distinctive for its sleek, glass façade and two distinctly shaped floor plates.

Mayor Michael Bloomberg and Larry Silverstein announce that West LB, a leading German financial institute, leased the top three floors of 7 World Trade Center, bringing the building's total occupancy to 85%.

Refinements to the plan included orienting the office lobbies westward, access to lower-level retail and the WTC Transportation Hub, and earning LEED gold certification. The three Greenwich Street Towers were planned to be models of life safety, cutting edge technology, and examples of environmental efficiency.

The Board of Commissioners authorized The Port Authority to enter into a long-term sub-net lease with JPMorgan Chase & Co. to develop Tower 5 as a 1.3 million-square-foot skyscraper at The World Trade Center site.

Governor George E. Pataki, Mayor Michael R. Bloomberg and Port Authority officials gathered to witness the placement of the first steel columns for 1 World Trade Center.

2006 marked the start of heavy foundation construction for the east bathtub, the installation of 1 World Trade Center's first steel, and the construction of the memorial's footings.

Moody's Corporation signed a 20-year lease to occupy 15 floors of the 52-story 7 World Trade Center. At approximately 600,000 square feet on 15 floors, beginning with the 12th floor, the Moody's lease is the largest to date at the World Trade Center and the largest lease transaction in Manhattan in 2006.

Silverstein Properties unveiled designs for Towers 2, 3 and 4 by architects Norman Foster, Richard Rogers, and Fumihiko Maki, respectively, along with a complete master plan for the entire east bathtub. For Tower 2, Foster designed a 78-story skyscraper that peaks with a slanted diamond-shaped top, recognizing the memorial below. Rogers' 71-story Tower 3 featured a slim glass box enclosed in an exterior steel frame of diagonal braces. Maki introduced a 61-story minimalist tower constructed in glass lined with perforated metal, intended to create a unique luster. A fifth office tower on Liberty Street, the Santiago Calatrava-designed WTC Transportation Hub, performing arts center, memorial and museum will complete the vision for the site.

Production of the first steel was produced in Luxembourg to create the first 27 "extra-large" steel columns of 1 World Trade Center. Approximately 805 tons of steel was being produced to serve as part of the below-grade structure for the historic tower.

He unveiled several final drawings to an audience of 700 engineers and architects at the AIA New York Chapter's 2006 Design Awards held at 7 World Trade Center. The revised design for 1 World Trade Center featured a 186-foot-tall podium which was redesigned to be covered by a screen of glass prisms, veiling the concrete base that was originally criticized for being too brutalist.

On May 23, 2006, Larry Silverstein opened 7 World Trade Center, a 52-story, $700 million project, that became New York City's first LEED-certified "green" office building.

Ground was broken for construction of 1 World Trade Center, the symbolic skyscraper designed to replace the destroyed World Trade Center. The tower will pay homage to the original twin towers, and will rise to 1,776 feet with its illuminated antenna.

Adamson Associates of Toronto was selected as the Executive Architect to lead a team of architects that would eventually included Foster & Partners, Rogers Stirk Harbour + Partnership (RSHP) and Maki and Associates.

The Port Authority of New York and New Jersey and Larry Silverstein reached an agreement in which Silverstein relinquished rights to develop the Freedom Tower and Tower 5 in exchange for financing with Liberty Bonds for Towers 2, 3, and 4.

Designed by Santiago Calatrava, the PATH was intended to accommodate 250,000 pedestrians per day. One of the innovative features of the design is that natural light will reach 60 feet below street level.

1 World Trade Center was redesigned due to security concerns by the NYPD and then-Governor George Pataki. Details such as the 1,776 height and the 276-foot spire remained the same. To comply with safety concerns, 1 World Trade Center would have no occupied space other than the lobby. It was also redesigned to be set back farther from West Street, a heavily trafficked highway. Many of the windows were planned to be tempered, laminated and multilayered for extra protection against explosions. The newly designed base has a smaller footprint and planned to be more of a square than a parallelogram.

The final design of the WTC Memorial and museum was unveiled by Arad and Walker. The design included two large "voids"-cascading reflecting pools thirty feet into the footprints of the Twin Towers. The design allowed visitors to follow ramps angled down the side of each footprint to an underground chamber that allows views. Names of all the victims, including rescuers and those who died in the 1993 Trade Center bombing are inscribed on a wall between the chamber and the pool. Extensive landscaping in the plaza featuring 400 swamp white oak and sweet gum trees will create a canopy over the plaza in the warmer months.

7 WTC topped out on October 21, 2004, ironworkers and city officials gathered in front of the building to celebrate the raising of the final steel beam.

Honoring the "enduring spirit of freedom", Mayor Bloomberg laid the cornerstone of the Freedom Tower, a 20-ton piece of granite inscribed with those words. The ceremony also included remarks from Gov. McGreevey, musical performances by the Young People's Chorus of New York City, Metropolitan Opera singer Morris Robinson, and a reading from the Declaration of Independence by the 12-year-old son a Port Authority police officer killed on 9/11.

Just days after construction began on 1 World Trade Center, Larry Silverstein announced that architects Richard Rogers and Fumihiko Maki would each design high-rise office towers at the World Trade Center site. Rogers Stirk Harbour + Partnership (RSHP) designed Tower 3 Fumihiko Maki designed Tower 4. These architects joined an impressive roster of architectural stars working at the site including site master planner Daniel Libeskin; David Childs of SOM designing the Freedom Tower; Santiago Calatrava, the architect for the transit hub; Michael Arad, who with Peter Walker, is responsible for the World Trade Center Memorial and Museum, and Lord Norman Foster for Tower 2. Following the announcement, Silverstein Properties set up a WTC design studio at 7 World Trade Center with architects, engineers, and consultants working together in an unprecedented collaborative spirit on the designs for Towers 2, 3 and 4.

Santiago Calatrava presented the design for the WTC Transportation Hub at the Winter Garden. The design evokes the image of a bird in flight. The building will be build with steel, glass, and light. To bring an even greater sense of open air and natural light to the station's concourse, mezzanine, and platform levels, Calatrava designed the hub's ceiling to retract-an innovative concept used mostly in sports arenas. Each level inside the station was designed to be column-free to create an open, bright space. Through this Transportation Hub, pedestrians will have access to Hudson River ferry terminals, PATH trains, 13 subway lines, and possibly a direct rail link to JFK International Airport. The Hub will be positioned at the northeast corner of the WTC site at Church and Vessey Streets and is expected to form an underground connection between the World Financial Center and the Metropolitan Transportation Authority's Fulton Street Transit Center.

Michael Arad and Peter Walker were selected as the designers of the Memorial ‘Reflecting Absence', honoring those lost in the terrorist attacks of September 11, 2001 and February 26, 1993. 5,201 submissions were received and the World Trade Center Memorial Competition, launched by the LMDC, became the largest design competition in history.

The shimmering skyscraper of glass, steel, and cable would stand at 1,776 feet, invoking the symbolism of the building. The building was designed to sit at the northwest corner of the site. The design also called for 70 commercial stories with 2.6 million square feet of office space, plus an underground regional transportation hub, garages, and several shopping centers. A public observation deck and a rebuilt Windows on the World, the restaurant that once sat atop the north tower was also in the plan. The previous World Trade Center buildings each had 110 stories, but 1 World Trace Center will rise higher because of a large glass structure and 276-foot spire topping off the building.

The station featured a canopy entrance along Church Street and a 118-by-12 foot mosaic mural, "Iridescent Lightning," by Giulio Candussio. The station was also ornamented with opaque panel walls inscribed with inspirational quotes attesting to the resilience of New York City. The panels partially shielded the WTC site from view. Since reopening after 9/11, the station has reclaimed its status as the busiest station in the PATH system.

Architect David Childs of Skidmore, Ownings & Merrill was selected to design 1 World Trade Center, planned to be the tallest of the five new WTC office towers. Mr. Childs is a graduate of Yale College and the Yale School of Art and Architecture. He joined the Washington, DC office of Skidmore, Owings & Merrill in 1971 after having served as the design director of the Pennsylvania Avenue Commission. David Childs then relocated to SOM's New York office where he worked on the New York Mercantile Exchange, the arrivals building at JFK, and Worldwide Plaza, among others. Differences of opinion quickly arose between Libeskind and Childs regarding their visions for the site's final result.

Calatrava is best known for his designs of public buildings and bridges. Some of his more recent work includes the Sundial at Turtle Bay in Redding, California, the James Joyce in Dublin, and the Olympic sports complex in Athens.

The Lower Manhattan Development Corporation announced the start of an international design competition for the WTC Memorial Site to commemorate those lost on September 11th and the 1993 bombings of the World Trade Center.

Libeskind's design was judged based on 12 points of criteria including price, public response, vision, connectivity, public space, and how the victims of the September 11th attacks would be memorialized. 1 World Trade Center is already the most famous element of architect Daniel Libeskind's WTC Master Plan. Libeskind's plan proposed a descending spiral of towers beginning at the site's northwest corner and ending at the National 9/11 Memorial and Museum, where the Twin Towers' footprints will be memorialized.

There were 2,000 entries in total. The seven semifinalists of this round of competition presented their designs at the Winter Garden of the World Financial Center.

Among its many building enhancements, 7 WTC included a reinforced concrete core and a steel superstructure. Safety systems exceeded New York City building code and are expected to form the model for future high-rise building codes. Construction on 7 WTC began soon after in 2002.

New York Governor George Pataki and New Jersey Governor James McGreevey created a World Trade Center site viewing fence with heroes' names and other information panels for visitors. The first steel column was also erected at the WTC site for the temporary PATH station.

The 1st round of the design competition for the reconstruction of the World Trade Center site took place, known as the "Preliminary Design Contest". However, the designs submitted for rebuilding the WTC were criticized as being too boring and placing too much emphasis on office space. This round of the design competition sparked debate about the future of the World Trade Center site.

The Federal Emergency Management issued a report on the collapse of 7 WTC on 9/11 based on a preliminary investigation conducted with the Structural Institute of the American Society of Civil Engineers confirming that the collapse was caused by fires on multiple stories ignited by debris from the other towers. These fires had continued due to lack of water for sprinklers or firefighting.

Beyer Blinder Belle is best known for its restoration of Grand Central Terminal while Parsons Brinkerhoff is one of the oldest U.S. private engineering firms involved in energy, environment and facilities engineering.

The Lower Manhattan Development Corporation was created in the aftermath of September 11th by then-Governor George Pataki and then-Mayor Rudy Giuliani to plan the reconstruction of Lower Manhattan and distribute nearly $10 billion in federal funds aimed toward rebuilding and revitalizing downtown Manhattan. The LMDC sponsored the international design competition for the World Trade Center Memorial. LMDC works in coordination with public and private sectors to coordinate long-term planning for the World Trade Center site and the neighboring downtown communities.

Two commercial jet planes struck the Twin Towers, causing their collapse and the destruction of four other WTC buildings. The attack killed 2,750 people at the Trade Center, many of them emergency responders. The collapse of 7 WTC, which had already been evacuated, followed at 5:20 p.m. that day due to a fire in the building. Soon after the attacks, Larry Silverstein announced his intent to rebuild.

Larry Silverstein completed the largest real estate transaction in New York history by acquiring the World Trade Center for $3.2 billion, only to see it destroyed six weeks later in the terrorist attacks on 9/11. Previously, the World Trade Center site was under the control of the Port Authority of New York & New Jersey. In this picture Larry Silverstein is joined by his children, Roger Silverstein and Lisa Silverstein, his wife, Klara Silverstein, and his attorney, Leonard Boxer.

Their goal was to knock the north tower into the south tower, bringing both towers down and killing thousands of people. The attack killed six people, including a pregnant woman, injured more than 1,000 people and created a five-story hole beneath the towers, resulting in hundreds of millions of dollars of damage.

The 610 foot 7 WTC was designed by Emery Roth & Sons with a red granite façade and a trapezoidal footprint. To supply power to the 10048 zip code, which was dedicated solely to the WTC site, Con Edison built an electrical substation located below 7 WTC in 1967. Tishman Realty & Construction managed construction of the building, which began in 1983. Some of the major tenants at 7 WTC were Salomon Smith Barney, American Express Bank International, ITT Hartford Insurance Group and Standard Chartered Bank.

Developed by Joe Baum and initially designed by Warren Platner, it occupied 50,000 square feet of space and offered breathtaking views of Manhattan. In its last year of operation (2000), Windows on the World reported its revenue as $37 million, making it the highest-grossing restaurant in the United States.

The Top of the World Observation Deck opens at Two World Trade Center (South Tower) on the 107th floor providing breathtaking views of Manhattan. On a clear day, visitors could see up to 50 miles in any direction.

A fire broke out on the 11th floor of the north tower. The fire then spread from the 9th to 14th floors by igniting the insulation of telephone cables in a utility shaft that ran between the floors. Most of the damage was concentrated on the 11th floor. Fireproofing protected the steel from melting and there was no structural damage to the tower.

The 24-year-old Petit made eight total crossings between the mostly finished towers, a quarter mile above the sidewalks of Manhattan, in an unexpected event that lasted about 45 minutes. Philippe Petit's high-wire walk is credited with bringing much needed popular attention and fondness to the Twin Towers.

The twin towers debut as the tallest buildings in the world -at 1,368 and 1,362 feet and 110 stories each-- surpassing the height of the Empire State Building until the Sears Tower in Chicago, providing 10 million sq ft of office space was built. The ceremonial opening of the twin towers on this date marked seven years of construction, preceded by more than a decade's worth of planning that transformed 16 acres of Lower Manhattan into an international business hub. In addition to the twin towers, four smaller buildings and a hotel, all built nearby around a central landscaped plaza, completed the complex. The mall at the World Trade Center, which was located immediately below the plaza, was the largest shopping mall in lower Manhattan. The six basements housed two subway stations and a stop on the PATH trains to New Jersey. Some 50,000 people worked in the buildings, while another 200,000 visited or passed through each day.

Some of the tenants in this building included Morgan Stanley; Verizon Communication; Thacher, Proffitt & Wood; New York Stock Exchange; Keefe, Bruyette & Woods; Fiduciary Trust Company International; and Dow Jones and Company.

The topping out ceremony of the north tower took place. The first tenants moved into the north tower, 1 WTC, although the tower was not fully completed until 1972. 1 WTC featured many innovations masterminded by Yamasaki and his team. Among them were the Twin Towers' high-speed elevators, sky lobbies, and "hollow tube" building model that distributed weight from the inner core across floor trusses to the exterior's closely spaced steel columns. The load-bearing exterior also served to brace against wind. Some of the major tenants at 1 WTC included Marsh USA INC, Bank of America, Cantor Fitzgerald Securities, and Brown & Wood LLP.

Demolition at the site began with the clearance of thirteen square blocks of low rise buildings for constru ction of the World Trade Center. Groundbreaking for the construction began on August 5, 1966. Site preparations were vast and included an elaborate method of foundation work for which a "bathtub" had to be built 65 feet below grade. The bathtub was made of a bentonite (absorbent clay) slurry wall intended to keep out groundwater and the Hudson River. Tie-backs were inserted through the wall and anchored at an angle in the earth behind them. WTC 1, the North Tower, rose ahead of WTC 2.

The design consisted of a square plan approximately 207 feet in dimension on each side. The buildings were designed with narrow office windows 18 inches wide, due to Yamasaki's fear of heights and his desire to make building tenants feel secure. The building facades were covered in aluminum-alloy.

Minoru Yamasaki was selected to design the project. Yamasaki was a second generation Japanese-American who studied architecture at the University of Washington and New York University. Yamasaki's designs often paid tribute to classical themes but his use of modern technology resulted in contemporary structures of glass and concrete. Yamasaki considered hundreds of different building configurations before deciding on the twin towers design and worked closely with the selected structural engineers of the project, Worthington, Skilling Helle and Jackson. Worthington, Skilling Helle and Jackson developed a tube-frame structural system which allowed for open floor plans without columns in the office spaces. Less than two years and more than 100 design concepts later, the Port Authority unveiled the $525 million World Trade Center plan to the public. It was a composite of six buildings comprised of 10 million square feet of office space. At its core were the Twin Towers, which at 110 stories (1,368 and 1,362 feet) each would be the world's tallest skyscrapers. Public sentiment ranged from astonishment at the sheer size of the towers, to both thrill and dismay at their monolithic, contemporary design.

SOM proposed a complete rebuilding and expansion of the financial district: the narrow streets would be closed while others would be widened, traffic would be redistributed and over 100 blocks razed. Various features of the SOM plan were implemented such as a Civic Center east of City Hall and a large marina on the East River that prefaced the South Street Seaport. SOM also suggested a World Trade Center. In 1958, Chase Manhattan Bank vice chair David Rockefeller announced plans to build a multi-million-square-foot complex on Lower Manhattan's east side. The Port Authority of New York and New Jersey agreed to oversee the building project.

The original proposal was for only one 70-story building, not the final twin towers design. Winthrop Aldrich, chairman of Chase Bank, was appointed to explore the feasibility of the project. The New York State Legislature passed a bill authorizing Thomas E. Dewey to begin developing plans for the project.

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Tallest building in the western hemisphere, visiting one world observatory nyc, one world observatory – nyc insider tips.

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One World Trade Center: how New York tried to rebuild its soul

When Ground Zero was finally cleared after the fall of the twin towers, New Yorkers trusted that thoughtful, ambitious urban design could make the city whole again. Why have they been so badly let down?

1WTC: as seen from around New York – in pictures

Y ou see it when you whip over the Brooklyn Bridge, or look downtown crossing Sixth Avenue: eight isosceles triangles of blue glass, taller than anything else on the skyline. One World Trade Center , finally approaching completion after 13 years of trauma and backbiting, has become a familiar, serene sight to New Yorkers – from a distance, at least.

Up close, at the foot of the tallest building in America, it’s a different story. Trucks pull in and out of construction sites. Commuters trek through scaffolding and mazes of blue tarp. Office workers shove aside dawdling tourists, or try to. Advertisements promise forthcoming luxury boutiques, while street merchants sell New York Police Department jackets for dogs. It is at once a place of frenzy and flatness. From some angles it looks like the future of New York – from others, not like New York at all.

In the plaza that many New Yorkers still call Ground Zero, two towers are open for business: 7WTC, a smaller building north of the site completed in 2006, and 4WTC, a sublime new office building to the east. But 1WTC – thankfully no longer called the “Freedom Tower” – has had its opening pushed back several times, and now seems set to welcome its first tenants in early 2015. Two further towers are deferred: 3WTC has had construction halted at eight storeys, while 2WTC has not yet begun to rise, and may never.

Also delayed is a new public transportation terminus for the World Trade Center site: the PATH (Port Authority Trans-Hudson) train, which connects Manhattan to New Jersey. Designed by Santiago Calatrava – currently being sued by his hometown of Valencia in connection with his crumbling Palau de les Arts – it should open in 2015, a full six years behind schedule, and comes with a $4bn (£2.5bn) price tag that exceeds the initial budget twice over.

And sitting in the middle of all of this is the memorial: two gargantuan fountains, each filling the exact footprint of one of Minoru Yamasaki’s destroyed towers, ringed by bronze railings bearing the victims’ names and set in an oversized, largely bare quadrangle. The only building on the superblock where the towers once stood is a small pavilion leading into the underground National September 11 Memorial Museum , which finally opened in May complete with airport-style security checkpoints.

Greenwich Street, a north-south axis eliminated by the old twin towers superblock, may have been reestablished to connect the site with Tribeca to the north. But the World Trade Center has not yet cohered into an organic, constituent part of the city. Office workers are nearly absent on the giant parvis, while tourists snapping selfies on the site of a mass murder stick to a few well-trafficked routes, beelining down Liberty Street and Vesey Street, as if the place was divorced from New York’s thrumming grid.

You would have thought that, 13 years after the attacks of 9/11, the outcome of the largest and most closely watched building project in the United States would be clearer. But the World Trade Center is still in limbo, its future as uncertain as New York’s.

A global, national and local catastrophe

The murder of nearly 3,000 people on 11 September 2001 was a national and international disaster. So were the wars and retributions that came after. But it was also a local catastrophe with an immediate political impact: it redeemed New York’s unpopular mayor, Rudy Giuliani, and opened the door for the election of Mike Bloomberg, the second Republican in a row in this overwhelmingly Democratic city. And there were hellish consequences for downtown’s infrastructure and economy; this was an attack on buildings and streets and tunnels and infrastructure, and its consequences not just political but urban too.

In the wake of the attacks George Pataki, a Republican then serving as governor of the state of New York, established the Lower Manhattan Development Corporation (LMDC), a commission of experts tasked with disbursing federal funds and supervising reconstruction efforts. The LMDC was challenged to imagine a new World Trade Center, but it also had to satisfy two big stakeholders: the site’s owner, the Port Authority of New York and New Jersey (a laughably incompetent and allegedly corrupt agency that also manages New York’s decrepit airports and bus terminal), and Larry Silverstein, a billionaire real estate developer who had leased the twin towers in a privatisation scheme in July 2001, and thus had a legal right to rebuild.

Pataki, who in those years of terror and illiberalism deluded himself that he might be president one day , milked his moment in the spotlight by insisting that “we will never build where the towers stood. They will always be a lasting memorial for those that we lost.” It was the first of many political decrees with direct, and not altogether salutary, urban consequences. From the start, the new World Trade Center could not be a living place that also memorialised the dead. It had to make their deaths visible at demagogic scale, 180 feet square times two.

Such was the backdrop for the design competition, a roller-coaster of an architectural showdown that brought out the worst in New York. A first round of entries was thrown out. Many big names stayed away – Rem Koolhaas, always the smartest man in the profession, figured out fast that he’d have more luck building in China. And the two finalists offered strongly divergent masterplans.

One, featuring a sunken memorial surrounded by a ring of five towers, came from Daniel Libeskind , who declared himself “the people’s architect” and took to wearing an American flag lapel pin at meetings. The other proposed a pair of massive, ghostly latticework structures, with a museum, a conference centre and theatre suspended above the twin towers’ footprints. This ambitious, less commercial proposal (which Libeskind publicly called “Stalinist”) was the work of Think, an ad hoc international team led by Rafael Viñoly, Shigeru Ban and especially the late Frederic Schwartz , a civic-minded architect often called the conscience of Ground Zero, who attended every meeting and ceremony and spoke frequently to victims’ families.

On 25 February 2003 – three weeks before the start of the Iraq war, which George W Bush tried to wage in the name of the World Trade Center dead – the LMDC chose Think, and informed Schwartz and Viñoly that they had won. They thought the decision was final. But the next day, Pataki and Bloomberg overruled their own committee (“There’s no goddamn way I’m going to build those skeletons,” Pataki told its chairman ). Libeskind suddenly got the job, setting in motion all the compromises and confusion that have come since.

By overruling his own committee, and by imposing Libeskind’s more traditional sequence of towers over Think’s innovative lattice structure, Pataki played directly into the hands of the man who more than anyone has shaped the new World Trade Center. That man is Larry Silverstein, a developer who not only sued his insurers for a double payout (there were two planes – pay me twice!) but also United and American Airlines for allowing the hijackers onboard. Proprietor of the twin towers for less than two months before they were destroyed, Silverstein has since pressured federal, state and city governments for billions of dollars in subsidies and tax abatements , shovelling risk and expense on to the public while ensuring profits accrue to himself. A grandmaster of state capitalism , Silverstein has held on through the endless delays, defections and budget overruns, outplaying not just Libeskind but the Port Authority too, and leaving no one in doubt that the most public tragedy in New York’s history took place on his private construction site.

Silverstein is no philistine – he is a significant philanthropist in New York – but he was not about to let aesthetic concerns override financial ones. On his watch, Libeskind’s designs were simplified almost to the point of disappearance, minimising their jagged forms into corporate quiescence. 1WTC – which Pataki (not Libeskind, as is often erroneously assumed) smarmily christened the “Freedom Tower” – would henceforth be designed by David Childs of the mega-firm Skidmore, Owings & Merrill. The pinnacle height remains 1,776 feet (after the year of the Declaration of Independence), but only thanks to an accounting trick: that measurement counts the antenna. Libeskind, after suing Silverstein and then settling with him, still has the title of master planner of the World Trade Center, even though almost nothing on the site is his idea.

A tranquilised New York

The tallest tower may glint on the New York skyline, but the site itself has receded from the public imagination. Delays became commonplace, markets collapsed, and major developments that should have stoked democratic anger elicited, in Bloomberg’s tranquilised New York , only bored acceptance. Back in 2006, at the end of his 12-year governorship, Pataki and Bloomberg brokered a deal to have the Port Authority take over construction of 1WTC, providing Silverstein a huge cut in rent on the remaining towers. It made New Yorkers perpetual landlords of a commercially unviable goliath, but nobody cared. Even when Occupy Wall Street electrified downtown New York in the autumn of 2011, neither the protesters nor their antagonists paid much attention to the giant tower rising one block away, which has cost $3.8bn in public funds – the world’s priciest skyscraper by far, more than twice the cost of the world’s tallest building, the Burj Khalifa in Dubai – and is at least partly to blame for climbing tolls on the city’s bridges and tunnels and a lack of funds to repair the city’s reprehensible infrastructure.

In Libeskind’s original vision, 1WTC was to be a jagged asymmetrical spire, rhyming somewhat with his fractured Jewish Museum in Berlin or Royal Ontario Museum in Toronto. Under Childs, it has become a leaden, compromised behemoth, whose chamfered corners resolve into a ho-hum sequence of triangular curtain walls. It’s tall, you can give it that – but at ground level, and for 15 storeys above that, 1WTC is a grim, unfenestrated fortress, cloaked in glass but made of concrete, on the orders of the New York Police Department. The post-2001 security state is inscribed on the World Trade Center, in visible and invisible ways. The new buildings incorporate extra emergency stairwells and bomb-resistant cores, while the streets are studded with bollards, and well-armed officers patrol the memorial square.

Silverstein has redeemed himself somewhat with the opening of the first of his three large towers – one of the finest works of architecture to arise in New York in years. At 978 feet, 4WTC is the seventh tallest building in New York, but unlike other recent skyscrapers – Renzo Piano’s New York Times headquarters in Midtown, say, or the outrageous One57 , a supertall condo for absentee billionaires – Fumihiko Maki’s tower, composed of two blocks of broad dark glass, withdraws into the sky and almost disappears on sunny days. 4WTC also has a commercial facade facing Church Street, one block east of the memorial, which will reportedly host a branch of the gourmet Italian food market known as Eataly, whose mobbed Chelsea location sees legions of gluttonous patrons snapping pictures of themselves with imported hams. Here you can see New York’s urban future more clearly: luxuries before necessities, consumption as culture – this is the grand Bloomberg legacy, and it is written across downtown everywhere from Broadway to Battery Park.

As for 2 and 3WTC, their fate remains uncertain, since nobody seems too keen on leasing in the buildings that are already on the market. Condé Nast, publisher of Vogue and the New Yorker, has rented 25 floors in 1WTC, aided by millions of dollars in tax incentives – the Port Authority even took on Condé’s current lease in Times Square. But despite the cachet of Anna Wintour and friends, 1WTC remains almost half empty. In the last three years, just one private company has inked a lease in the tallest building in New York, an advertising agency that took the 87th floor. The 16 floors beneath that are all yours if you want them, though even after a price chop last spring they’re still $69 a square foot, well above market average.

4WTC, which belongs to Silverstein even while being funded with $1bn in financing from the Port Authority, had no renters for years except the city of New York and the Port Authority itself. (This May, 4WTC finally landed a private sector tenant, another ad agency.) 3WTC, designed by Richard Rogers , now seems a goer after yet another ad agency, this one a WPP subsidiary, signed on as principal tenant. 2WTC, Norman Foster’s , has had interest from bailed-out Citigroup but nothing definite.

But economics were never the motivating factor at the World Trade Center at least on the government’s side. Lower Manhattan lost approximately 11 million square feet of office space on 9/11, but the 5 million square feet of 1 and 4WTC got dumped on the market in the wake of Lehman Brothers’ collapse , which led to significant restructuring in the financial sector – traditionally the biggest renters downtown. The urban design of the World Trade Center has always been negotiated at the unhealthy conjunction point of sentimentality and commerce, with political and emotional desires jostling against hard-edged business motives. Cannier private developers have played that sentimentality to their advantage. Public interests have not been so lucky.

Short straw

If you really want to see how the public drew the short straw at the World Trade Center, go underground. Public transportation should have been the glory of any downtown redevelopment: nearly all of the city’s subway lines converge in Lower Manhattan, along with the commuter train from New Jersey. Yet in the summer of 2014, commuters are still trudging through a maze of temporary structures, while the World Trade Center Transportation Hub, designed by the disastrous Calatrava , languishes unfinished. The hub has metastasised into by far the most expensive rail station in history, an insane $4bn for a low-traffic terminus (the city’s 10th busiest) that doesn’t even expand capacity. Half a decade overdue, outrageously over-budget, the final design will not even incorporate Calatrava’s spiffier elements: the “wings” of the roof that could be opened on sunny days are now non-functional. It is a bona fide catastrophe , especially considering the woeful state of New York’s subways; a new line along Second Avenue has now been delayed for 85 years .

Then there are the memorial and museum, which have had mixed fortunes. The museum, which opened in May and elicited criticism for its exhibitions and its tacky gift shop, has been attracting visitors – out-of-towners mostly – despite its $24 admissions charge (a consequence of he-said she-said bickering between federal and local governments as to who should support the institution). Its main exhibition spaces lie down at bedrock, facing the huge slurry wall that kept the Hudson River from flooding the lower levels of the twin towers, and which held fast on 9/11. Whatever the museum’s faults, this moist industrial wall, stretching 68 feet up, is something to see. It is the one major evocation of the original World Trade Center that remains on site, and the only place where I feel the sadness, hope and civic righteousness that the new World Trade Center ought to inspire.

Libeskind’s masterplan would have placed the memorial to the dead against the slurry wall, but that got scrapped too. Instead it is at street level, in a massive new square whose few trees and benches don’t do enough to make it work as a public space. The memorial, designed by Michael Arad, does at least evade the rightwing kitsch of some other 9/11 commemorations (nearby is a despotic bronze statue of an American soldier on horseback, paid for by private funds). But its remembrance-for-dummies style – the names of the dead plus waterfalls, at the giant scale Pataki demanded – hasn’t commended it to New Yorkers, and while it looks alright from the 57th floor balcony of 4WTC, at ground level it remains divorced from the fabric of the city.

On three visits this summer, I found the site busy every day. Children run about, untroubled by the security apparatus, and the volume is loud; it is a site of amusement rather than meditation. Fine, but then where are the office workers, where are the apartment dwellers of Battery Park? If it isn’t contemplative, shouldn’t it be urban? What should have been the centre of a massive redevelopment, one for locals and visitors alike, has instead become a lacuna in New York’s grid, a foreign exclave in the middle of a city of eight million.

As for the future of culture at the World Trade Center, that may be the trickiest problem of all. Numerous cultural institutions, among them the Signature Theatre, the Drawing Centre and the now-defunct New York City Opera, had envisioned a move downtown. But during the planning process Pataki, still in presidential-wannabe mode, proclaimed: “We will not tolerate anything on that site that denigrates America, denigrates New York or freedom” – and this threat of censorship was enough to send many prospective tenants packing. A site is still designated for a cultural institution, but its location between 1WTC and the PATH terminal guarantees headaches for construction, and Frank Gehry , the project’s initial architect, was dismissed last week . Still, there will be Eataly, there will be 50 different kinds of olive oil to buy! In the city that Bloomberg made, that may be culture enough.

Street-level politics

When the pit was at last cleared, the remains of the dead accounted for and the carcinogenic rubble carted away, New York was ready to wager that thoughtful, ambitious urban design could make the city whole again – or remake it, actually, as something even better than the financial capital disrupted by Yamasaki’s superblock. It didn’t happen. But 13 years on, it’s easier to see the World Trade Center as something more complicated than an autonomous urban design debacle. Rather, it is a symptom of larger urban conditions that, even with the election of the leftwing Bill de Blasio as our new mayor, show no signs of abating.

In the early 2000s, lower Manhattan was principally a site of trauma. In 2014 it evokes other, fresher troubles, among them massive income inequality, the impunity of the financial sector, a do-nothing Congress and a state government corrupted beyond redemption, and a record tourist influx that’s the flipside of the city’s gentrification and pacification. Politics play out on the level of the street. Aesthetics and design are not enough.

Ultimately, the moral of the new World Trade Center is that you can’t just plug an urban scheme into a grid and wait for results. You need community, solidarity and civic virtue – ideals that flickered for a moment in the hazy, uncertain days of late 2001, but that disappeared in the era of Bloomberg and were replaced by the privatisation and oligarchy that are the hallmarks of the 21st century.

Public infrastructure has languished while private arrangements have grown. Billions and billions of public dollars have been drained while private cash has been hoarded. And New York now has a modestly improved street plan, one great tower, a few OK ones, an acceptable museum, an unworthy memorial, a scandalous transit hub and, sooner or later, a lot of new places to shop. The World Trade Center: it could have been worse! But if that’s all we expect from New York, then maybe we should move somewhere where the average rent isn’t $3,451 a month.

Vivienne Gucwa’s new book is NY Through the Lens

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Watch the 11-Year Construction of One World Trade Center in this Time-Lapse

• Written by Joey Jacobson
• Published on June 06, 2015

In recognition of the opening of One World Observatory in New York City , EarthCam has published a full time-lapse of One World Trade Center's construction. Thousands of high-definition images capture the incredible undertaking of construction and planning that took place from October 2004 to Memorial Day 2015. The camera flies the viewer across the site, showing how the building and its surroundings have taken shape over the past 11 years.

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A look inside the new One World Observatory

May 20, 2015 / 7:00 AM EDT / CBS News

Three to four million people are expected to come to One World Observatory during the first year. While the views are the stars of the show, designers have added other attractions, reports CBS News correspondent Anthony Mason.

Every trip to the top of the One World Trade Center starts with a step back in time.

The ride to the 102nd floor is a visual history lesson. Visitors see New York City's transformation from wetland wilderness to modern metropolis.

The man behind it all is David Checketts. He used to run Madison Square Garden but is now the CEO of Legends, the company that operates One World Observatory.

"This is the fastest elevator in the world," Checketts said."This is 47 seconds from the bottom to the top. Now you'll notice over here the building is being built around you. And then all of a sudden we're at the top."

In most skyscrapers, the view hits you immediately. Not here. A video show builds the suspense before the city is unveiled.

On a clear day, visibility seems almost endless, thanks in part to the 30-foot windows that extend all the way around.

You can see the Empire State Building, the Statue of Liberty and the Brooklyn and Manhattan Bridges.

"You're high enough up that you can start to see the curvature of the earth," Checketts said.

One thing people won't see, however, are explicit reminders of 9/11, unless they look down at the memorial pools below.

"This space was to be used as a fist pump. We put it back up and now, looking forward to a future filled with promise," Checketts said.

New York City Mayor Bill de Blasio called it "a rebirth."

"It means that, particularly for downtown, we're back 100 percent. Downtown is thriving right now. Great companies are coming down here to create the world headquarters. Big residential community here, ironically much more of a residential than 20 years ago. And it's a great moment," de Blasio said. "It really says that we have turned the corner once and for all, and those that sought to attack us lost, once again."

The observatory spans the top three floors of One World Trade Center.

"The view from here is unlike any other that I've ever seen," CNN anchor and "60 Minutes" correspondent Anderson Cooper said. "And it really gives you a sense of the history of New York ... why Manhattan is where it is, the geography of it and you really feel rooted in the history. Often in New York it's hard to get a sense of a place, you don't see much sky but here you see it all, and it's -- you literally see the curvature of the earth. It's amazing."

"The challenge was to do something creative enough so that people didn't just come up, look out, take pictures, and then go back down," Checketts said.

At the Sky Portal, embedded in the floor, you can look down at the streets below. The view comes from a live high-definition feed from a camera affixed to the spire at the top of the tower.

Guides will help tourists learn about the city's attractions, or if smaller screens are more your size the experience offers One World Explorer iPad with a virtual helicopter tour of the city. Select different locations on the screen and the chopper takes you right there.

The ride down on the elevators feels more like a flight simulation as passengers are sent on an aerial tour around the building, and it's just as stunning at night.

Unfortunately, there is no outdoor space at the observatory. Checketts said the building's design wouldn't allow for it.

"What a message to the world. We said we were going to build it back and build better than ever, and it's true. You can see it," de Blasio said.

Ticket prices range from $26 for young children to $32 for adults.

• First look at a sunrise from One World Observatory
• First GoPro tour inside One World Observatory
• "CBS This Morning" makes history with first broadcast from One World Observatory

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One World Trade Center (1 WTC), New York, US

One World Trade Center (1 World Trade Centre - 1 WTC), built where the twin towers of the World Trade Center (WTC) once stood, opened for business on 3 November 2014, more than 13 years after the 9/11 attacks.

Skidmore, Owings and Merrill (SOM)

Master Plan Architect

Studio Daniel Libeskind

Construction Manager

Tishman Construction Corporation

Silverstein Properties, Inc

Wind Surveyor

Rowan Williams Davies & Irwin

Construction Started

One World Trade Center (1 World Trade Center – 1 WTC), built where the twin towers of the World Trade Center (WTC) once stood, opened for business in November 2014, more than 13 years after the 9/11 attacks.

Designed by Skidmore, Owings & Merrill (SOM) LLP, 1 World Trade Center is the tallest building in the western hemisphere. It achieved the LEED Gold certification in September 2016.

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1 World Trade Center marks the rebirth of a major financial and commercial hub, re-establishing New York City as the epicentre of high-rise skyscraper design and serving as a symbol of the revitalisation in lower Manhattan.

The tower’s façade installation was completed up to the 71 st floor by March 2012. The building reached 100 storeys in April 2012. The final two sections of the steel spire were installed by May 2013.

An awe-inspiring $610m National 9/11 memorial and museum was inaugurated in May 2014. The site accommodates four additional skyscrapers (Towers 2, 3, 4, and 7). Tower 7 was the first to open in May 2006.  It was followed by towers 4 and 3, which were opened in November 2013 and June 2018.

The WTC amenities include a 16-acre campus consisting of trees and modern architecture. The campus houses multiple dining, entertainments and shopping options covering up to 450,000ft² area.

Project background

1 World Trade Center was originally named ‘Freedom Tower’ to demonstrate the US’s triumph over terrorism. In March 2009, the name was changed to One World Trade Center by the Port Authority of New York and New Jersey for easier identification. The centre’s role is similar to that of the old twin towers. The building contains 3.5 million square feet of space across 104 stories, of which 2.6 million square feet is office space. The 1 World Trade Center is built at the old tower 6 site.

At its base, street-level lobbies provide access to offices and public areas, in addition to the observation deck and restaurants near the top of the building. Below-grade concourses connect directly to 15 subway lines and to transit hubs for the Port Authority Trans-Hudson (PATH) commuter train service to New Jersey.

Although many people associate the design of 1 World Trade Center with architect Daniel Libeskind, his only responsibility is for the master plan of the WTC site. He determined the layout of the buildings, the location of the memorial and, in collaboration with the stakeholders and their architects, the distribution of the programme area. He also worked with SOM on a design that has since gone by the wayside.

He called for 1 World Trade Center to have a spire of 1,776ft (541m). The figure ‘1776’ represents the year that the founding fathers of the US signed the Declaration of Independence, asserting the country’s independence from the UK.

Changes to the original plans for New York’s 9/11 memorial

Beyond that, SOM is the primary firm behind the current 1 World Trade Center design. The company was also responsible for the twisted tower concept that preceded it. In that version, the glass-clad tower’s asymmetrical form would have alluded structurally to the nearby Statue of Liberty.In particular, the offset spire rising 400ft above the tower would have mirrored the statue’s raised Torch of Freedom.

However, that design was not adopted for both cost and safety reasons. Its glassy base had worried the New York City Police Department (NYPD). As part of the NYPD’s requirements, the revised design included a concrete protection wall around the lobby, prompting criticisms that the base would resemble a bunker.

The building concept, therefore, underwent significant revision. The goal was to simplify the design and enhance security while avoiding previous issues.

1 World Trade Center design and immense size

The new shape plays with geometry and perceptions. The base is a 200ft x 200ft (61m x 61m) square and the first 20 storeys rise straight up, aligned with this square. The design was revised twice in June 2005 and in June 2006 to cover the concrete base with a screen of glass prisms.

From the 20 th floor up to a 1,368ft-high parapet, the edges chamfer back, creating eight triangular planes. The square rotates until the 102nd-floor square has turned 45° from the square on the 20th floor.

The eight, elongated, isosceles triangles form a neat configuration on the façade. These alternate between triangles with the apex on the 102nd floor and those with the apex at the 20th floor. The downward-facing triangles slope inward slightly, which is to say that the footprint of each floor shrinks slightly at higher points.

The parapet at the top of the topmost floor clearly marks elevations of both 1,362ft and 1,368ft. These represent the heights of the destroyed twin towers. A three-level One World Observatory deck is located in the 100-102 floors. Visitors can reach these heights via five high-speed elevators (just some of the building’s 54 elevators).

Above that level is the communications ring. This contains equipment for electronic news gathering, whip antennae and microwave relay dishes that television stations and businesses will use.

An illuminated 450ft tapered spire crowns the building and the entire WTC site. It also serves as an antenna providing digital broadcasting for the area (a function temporarily served by the Empire State Building). The top of the antenna also brings 1 World Trade Center up to the requisite 1,776ft height.

At the tip of the antenna, a brilliant, slowly rotating beacon flashes the letter ‘N’ in Morse code, as lightships once did in great harbours of the world. The ‘N’ stands for ‘New York’.

At 1,776ft, 1 World Trade Center is more than 400ft taller than the twin towers but not the world’s tallest structure. That distinction goes to the 2,717ft-tall Burj Khalifa, and SOM-designed tower in the UAE Burj Jumeira, which opened in 2010.

The building holds a 408ft spire, which sits on a concrete core at the top of the tower.

Materials used to build Manhattan’s 1 WTC

1 World Trade Center is clad in ultra-low-iron glass with stainless-steel for the corners. The stainless-steel harks back to the twin towers, where the corners catch the rays of the setting sun and glow at sunset.

In order that the building is not read as a bunker, the 20-storey base of 1 World Trade Center is encased in prismatic glass. As demonstrated in mock-ups, the prisms will refract and reflect light, trees and the sky by day, then shimmer at night.

On the west plaza of the tower, illuminated, stainless-steel steps serve as a gathering place, providing a gentle transition between the building and the plaza itself. This is an improvement over the twin towers, which had a much more abrupt transition.

The centre has been built using 48,000t of steel, along with 13,000 exterior glass panels.

Safety features of One World Trade Center

Given the controversy over the structural soundness of the twin towers, safety has been a key construction issue. 1 World Trade Center incorporates systems that far exceed the requirements of the city’s building code.

The building features structural redundancy and extra-strong fireproofing. The elevators are housed in a protected concrete building core. Moreover, the extra-wide, pressurised stairwells lead directly to outside streets and other stairwells are dedicated for use by fire-fighters.

Additional safety features include concrete-protected sprinklers, emergency risers and enhanced emergency communication cabling. The entire World Trade Center site is supported by a police command centre.

1 World Trade Center construction by Skidmore, Owings and Merrill (SOM)

The slow progress since the 2004 groundbreaking has provoked complaints and criticism. But SOM explains that they’ve faced complex challenges because the surrounding areas below grade contain tracks for PATH, a commuter train running from New York to New Jersey. Existing PATH structures must remain in place during the construction of 1 World Trade Center, which poses challenges.

SOM noted that because of the high construction costs in New York City, it’s not at all unusual for a foundation to go in while architects complete the design of a building.

Tishman Construction Corporation is the construction manager for the 1 World Trade Center project. The project uses low-energy HVAC solutions, high-performance façades, renewable energy sources, non-ozone-depleting chemicals, and recyclable and sustainable materials, including rainwater collection systems.

The tower’s first entrance, a street-level plaza on the eastern side, took shape in July 2009 with a concrete pour of approximately 1,250yd³.

The entrance above the street level forms the base of a large fountain on the plaza level and for planting swamp white oak trees. The section of the tower’s plaza was completed five storeys underground and core rises about 100ft above the ground.

A total of 22,000yd³ of concrete was poured at the site and nearly 700t of steel was installed for the tower’s substructure.

Transportation infrastructure surrounding New York’s 1 World Trade Center

The Port Authority of New York and New Jersey invested approximately $4bn for construction of a state-of-the-art railway station and associated structures at 1 World Trade Center. Designed by Spanish architect Santiago Calatrava, it consists of the World Trade Center Transportation Hub, shopping mall and pedestrian network. The facility was opened in 2016, replacing the old temporary PATH station.

A contract to fabricate, furnish and erect the World Trade Center Transportation Hub was awarded to DCM Erectors in March 2009. The $338.8m steel contract includes a transit hall, pedestrian links to the centre’s commercial complex and providing permanent support to Greenwich Street and the No. 1 subway box.

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1 World Trade Center: A high-tech ride symbolizing New York’s resilience

Inside One World Observatory

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From the bedrock of lower Manhattan, a new tower has risen to claim a place of prominence in an ever-resilient city.

Such is the message driven home during the slick, high-tech presentation that accompanies a visit to the new observation deck at 1 World Trade Center, the 1,776-foot, recently completed office tower that is the city’s tallest building.

Friday’s opening of One World Observatory on the 100th, 101st and 102nd floors is a milestone in the years-long redevelopment of the site that once housed the twin towers, destroyed in the terrorist attacks of Sept. 11, 2001.

For the first time since the attacks, the general public will be streaming into a World Trade Center skyscraper and speeding to the top in elevators — 47 seconds from below ground to the 102nd floor — to take in spectacular views of the metropolis and beyond.

Though the events of Sept. 11 are not ignored, the focus of the new observatory’s “experience” is very much on renewal and celebrating New York and all its offerings.

“We want that fist-punch moment that says, ‘We’re back,’” said Dave Kerschner, president of attractions for Legends, the company that operates the new observatory.

That “ah-ha” moment comes during a choreographed presentation before anyone even steps foot into the observatory.

Upon arrival, visitors descend into a white marble lobby for security checks. From there, they enter a welcome hall where a huge interactive map of the world displays real-time data on visitors’ home states and countries scanned from their ticket stubs.

Visitors then move into a darkened corridor lined with video screens playing snippets of interviews with construction workers, architects, planners and other people who were involved in the building of 1 World Trade Center. This is one of the few times Sept. 11 receives mention, when many of the workers describe how meaningful it was for them to be part of the rebuilding effort.

The corridor continues through a section of exposed granite bedrock on which the skyscraper is secured, ending at a bank of elevators, which Legends says are the fastest in the Western Hemisphere.

The theme of an ever-changing, vital city is introduced during that quick ride to the top. Three sides of the elevators are lined floor to ceiling with LED screens that show a time-lapse video of what New York looked like from the 1500s until now. Scenes of bucolic village life of the city’s origins dissolve into the bustling immigrant center it was in the 19th and early 20th centuries into the early skyscraper era to present day.

Briefly, the old World Trade Center buildings are seen on the right-side screen. “The twin towers appear and disappear at the appropriate time,” Kerschner said.

At the entrance to the observatory, visitors enter a long, narrow room in which they face a wall with yet more screens. A montage of New York scenes — pedestrians pounding the pavement, the lights of Times Square, Chinatown, the High Line park, an iconic water tower — plays to music. Then, the sensory overload stops.

It is quiet and the wall of screens rises like a curtain in front of a stage to reveal the first view — looking north up the island of Manhattan.

There it is, the “ah-ha” moment.

Once upstairs, visitors can roam the main observatory floor with its 360-degree views of the city, grab a bite in one of three restaurants on the 101st floor that are open only to visitors who paid the observatory’s $32 entrance fee or step on the Sky Portal, a round glass floor under which is played live-streamed video of the street scene below taken from cameras attached to the building’s spire.

For the people who have been overseeing the redevelopment of the 16-acre World Trade Center site, the observatory’s opening is one step in many over the last few years — the creation of the memorial pools in the footprints of the former towers, the opening of the National September 11 Memorial and Museum, the construction of 4 World Trade Center, another office tower, and the arrival of the first tenants to 1 World Trade Center.

The observatory “brings closure on 1 World Trade Center,” said Patrick Foye, executive director of the Port Authority of New York and New Jersey, the public agency that owns the site and sees this as part of the city’s revival.

That more work is still to be done was evident during a walk through the area. Workers on cherry pickers painted the giant spikes protruding from the Santiago Calatrava-designed transit hub, set to open in stages this year.

Steelworkers welded supports on 3 World Trade Center, the next high-rise to go up on the site, and yet more work continued on the fortified vehicle security building being constructed on the southern border, which will have a rooftop park.

Steven Plate, director of World Trade Center construction at the Port Authority, said the new observatory also brought back a cherished place for New Yorkers, who used to go to the old World Trade Center observation deck to celebrate anniversaries and weddings and to make marriage proposals.

He had just such an experience. In 1975, Plate said that for their first date, he took the woman who became his wife to Windows on the World, the former restaurant atop the original World Trade Center.

“It was the middle of winter and it was snowing and we went to the bar,” he reminisced. “And now we’re going to go back.”

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https://www.nist.gov/blogs/taking-measure/20-years-later-nists-world-trade-center-investigation-and-its-legacy

Taking Measure

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20 Years Later: NIST's World Trade Center Investigation and Its Legacy

The collapse of the World Trade Center (WTC) buildings following the terrorist attacks of Sept. 11, 2001, was one of the worst-ever building disasters in recorded history — killing 2,749 people. More than 400 emergency responders were among those killed, the largest loss of life for this group in a single incident.

I was shocked to learn of the 9/11 terrorist attacks, along with the rest of the nation, while attending a conference in Krakow, Poland. My immediate thoughts that Tuesday turned to the safety of my family back home. Once I talked to them and knew they were safe, I decided to fly to Berlin since that would give me more options to get home quickly once flights resumed over U.S. airspace. Over breakfast at the Berlin hotel that Friday, I began sketching out initial ideas for our response that would involve a reconnaissance and assessment phase followed by a more detailed investigation.

A few weeks later, other National Institute of Standards and Technology (NIST) leaders and I began briefing policy leaders at the Department of Commerce, the parent agency of NIST. We explained the ways in which our agency could help determine the technical reasons why the buildings collapsed — and how this knowledge could not only provide answers for all those affected by the WTC disaster but also help make all buildings safer in the future. Meeting with House and Senate congressional staff, we discussed the lack of adequate authorities for any government agency, not just NIST, to conduct technical investigations into such building collapses. We reminded them about NIST’s long history and expertise in conducting disaster and failure studies , from the Gulf Coast structures destroyed by Hurricane Camille in 1969 and the 1971 San Fernando earthquake to the collapse of the Kansas City Hyatt Regency Hotel walkway in 1981 and the collapse of Connecticut’s L’Ambiance Plaza building in 1987.

After numerous briefings and two hearings at which the NIST director and others testified, Congress enacted, and the president signed into law, the National Construction Safety Team (NCST) Act of 2002. This law, for the first time, gave NIST a comprehensive set of authorities to conduct technical investigations in the wake of any building failure that resulted in substantial loss of life or posed a significant threat of doing so. Congress directed $16 million to support the NIST investigation as part of an emergency supplemental appropriations for the 2002 fiscal year.

I had the unique opportunity and privilege to be engaged in every aspect of the investigation from its conception, planning and budgeting to its execution, communication and the implementation of its recommendations via standards, codes and industry organizations. I was appointed to lead the WTC investigation while serving as chief of the Structures Division, just seven years after I had joined NIST from the Massachusetts Institute of Technology (MIT). I embraced this immense new responsibility to help find out what happened on that day and what, if any, actions should be taken to make our buildings more resilient.

The NIST team for the WTC investigation included approximately 85 staff members from across the agency. But the investigation was not done only by NIST. The full investigation team consisted of more than 200 people, including world-class scientists and engineers from industry and academia, to help us meet the challenges of the investigation’s unprecedented scope, scale and technical complexity. The investigation team acted tirelessly with dedication to and in memory of the lives that were lost on that day, and with the complete objectivity and integrity that have guided NIST over its 120-year history. Our investigation also benefited from the new NCST Advisory Committee established by Congress and made up of highly respected non-NIST experts from industry and academia.

The WTC buildings collapsed from many different factors working together in a complex fashion. Our investigation used physics-based computer simulations together with the available evidence. These very large-scale computations took into account the multiple impacts of airplane and debris, the spread of multi-floor fires ignited by jet fuel or flying debris, the heat-related weakening of structural components with intact or dislodged fireproofing materials, and the complex responses of the building structures leading to their collapse. Successfully combining state-of-the-art computational tools in ways that had not been done before, a single end-to-end simulation on then-existing computing resources took about two months to carry out for one of the WTC towers and eight months for WTC 7. We conducted live fire experiments that ranged from the simple (to gather data on burning characteristics of the jet fuel) to the more complex (a complete WTC office mock-up with furnishings). These experiments validated the computer simulations that would ultimately determine the probable collapse sequence for each building and guide many recommendations.

We relied on extensive evidence — combined with careful and detailed review, analysis and testing — to build our models, and validate our simulations, hypotheses and findings. This evidence included 236 major structural steel components, 7,000 video segments, more than 7,000 photographs, emergency responder communications, published accounts of evacuation from 400 survivors, and a large collection of design, construction, maintenance and inspection documents for the three buildings.

We conducted extensive interviews with more than 1,000 surviving occupants of the World Trade Center buildings to analyze occupant behavior and evacuation during emergencies. We also interviewed 116 emergency responders to document and assess their operating protocols and wireless communications in large-scale events and challenging radio-frequency environments such as those encountered in the WTC buildings.

We coordinated with the National Commission on Terrorist Activities Upon the United States (the 9/11 Commission) and the City of New York in the planning and conduct of emergency responder interviews. This enabled 9/11 Commission staff to participate in these interviews alongside NIST staff. We also engaged extensively with local authorities and key stakeholders in New York City, including the families of victims and professional organizations, and with other federal agencies such as the Federal Emergency Management Agency (FEMA) and the National Transportation Safety Board (NTSB).

The NIST team ensured that the investigation was conducted in an extremely open and transparent manner given the intense interest of the public — especially families of victims, local authorities and industry — who held many different perspectives on the reasons for the building collapses and loss of lives. We met regularly with diverse stakeholder groups, soliciting and considering their input in developing the investigation plan, findings, recommendations and final reports. We provided detailed updates and answered wide-ranging questions at 23 public meetings and briefings (with seven in New York City), issued seven news releases and media updates, and maintained a comprehensive, publicly accessible website during the investigation.

As a result of the exceptional teamwork in our investigation, we were able to overcome the many technical and nontechnical challenges, while maintaining the highest degree of quality, objectivity and credibility. We are deeply grateful to all of the people who worked with NIST, provided photos and other critical information, and gave unstintingly of their time to support and help us successfully carry out the largest U.S. building failure investigation ever conducted.

NIST released 47 reports from our investigation — totaling about 11,000 pages — which included robust science-based findings and conclusions, as well as recommendations for major safety improvements to U.S. buildings. We determined why and how each of the 110-story WTC towers collapsed following the initial impacts of the aircraft and why and how the 47-story WTC 7 collapsed; whether the injuries and fatalities were high or low depending on location, including all technical aspects of fire protection, occupant behavior, evacuation and emergency response; and what procedures and practices were used in the design, construction, operation and maintenance of these buildings.

The NIST recommendations resulted in more than 40 major and far-reaching changes to U.S. building and fire safety codes to improve the safety of buildings, their occupants and emergency responders. These recommendations were not designed, however, to make buildings withstand aircraft impact. It would be better instead to keep terrorists away from airplanes, and airplanes away from buildings.

Our recommendations have already had significant impact on design and construction practice for high-rise buildings in New York City, across the U.S., and around the world. We now see evidence of more resilient construction such as wider stairways with hardened enclosures, increased fire resistance rating for structural frames, significantly improved bond strength for fireproofing materials so that it is difficult to dislodge them from the structural steel they are protecting, and more robust radio communications coverage within buildings for emergency responders. 

Now, 20 years later, I have found that this event has had a profound effect on the arc of my career and life’s work by opening up many new opportunities to advance impactful research and innovation for our nation. The impact our recommendations have had on U.S. building and fire codes and standards has been our greatest accomplishment, especially seeing as the federal government does not have any regulatory authority over them. Instead, standards and codes development organizations quickly adopted them. Changes to the nation’s building and fire codes and standards — stemming from our proactive efforts to engage the standards and codes bodies — were history-making due to the extraordinary magnitude of the safety improvements, uncharacteristically rapid speed with which such major changes were adopted (less than five years), and exceptional support of the nation’s building and fire safety officials. These changes have significantly advanced the safety and protection of America’s buildings, their occupants and emergency responders in future disasters.

NIST rarely — if ever — had experienced such active public and media interest during — and after — an investigation or study. We have reviewed other WTC studies that have come out since we completed our investigation, including those that consider alternative hypotheses for the WTC building collapses. Based on our exhaustive analysis and the evidence available to us, NIST continues to stand behind the findings and recommendations of our investigation.

The WTC investigation also had a profound impact on NIST itself. Based on our experience from the WTC investigation and our new investigative authorities, we began a formal NIST program in 2010 to coordinate disaster and failure studies. This program has allowed NIST to respond more rapidly and effectively to incidents such as the May 2011 tornado in Joplin, Missouri, and the June 2021 collapse of the Champlain Towers South Condominium in Surfside, Florida.

It also enabled NIST to initiate, develop and establish a world-class disaster resilience program beginning in 2007. This program is transforming the safety of buildings and infrastructure systems to a comprehensive community-based approach. In recognition of our WTC work, Congress designated NIST as the lead federal agency to oversee the $130 million per year, multi-agency U.S. National Earthquake Hazards Reduction Program (NEHRP) in 2004. Congress further enacted the National Windstorm Impact Reduction Act in 2004 and designated NIST as its lead agency in 2015. We have achieved significant advancements in structural fire engineering practices through new standards and guidelines. This effort continues via a unique new NIST facility — the National Fire Research Laboratory — to test the performance of real-scale structures under realistic fire and structural loading. Today, our disaster resilience program is addressing the risks of climate change to our communities due to the increasing frequency and severity of hurricanes, tornadoes and fires at the wildland-urban interface.

I visited New York City frequently and spent a considerable amount of time there during the investigation, and continue to often visit the city. Our team received excellent, vitally needed support and cooperation from New Yorkers. New Yorkers are extraordinarily resilient. Just look at how they responded to the tragic events of 9/11. It is gratifying to see all the great progress that has been made in fully rebuilding the World Trade Center complex and the many new safety features that have been implemented consistent with our recommendations.

In 2014, my family and I had the privilege of visiting the largely underground 9/11 Memorial and Museum as well as the newly built 104-story One World Trade Center. The curators who were planning the 9/11 museum came to NIST several times to look at pieces of World Trade Center steel that were under investigation at the time. The curators ended up selecting pieces of steel that are now in the museum. They include two large exterior columns that were struck by the aircraft when it crashed into WTC 1. These visits were emotional experiences for me since they brought back vivid memories of the tragic events and consequences of that day and how far we have come as a nation since then. I am very proud of what the NIST team accomplished through our investigation and the lasting impact of the resulting changes on the safety and resilience of our nation’s buildings, their occupants, and emergency responders.

Read other blogs in this series:

How 9/11 Changed Me and First Responder Communications

Putting Together the Big Picture for the World Trade Center Disaster Investigation

Analyzing the Aftermath of the Twin Towers Aircraft Impacts

Reflections on Assisting With the 9/11 World Trade Center DNA Identifications

Inside the Towers on 9/11: My Story of Investigating the WTC Evacuation

Reconstructing the Fires That Brought Down WTC 1, 2 and 7

About the author

S. Shyam Sunder

S. Shyam Sunder led the Federal Building and Fire Safety Investigation of the World Trade Center Disaster in the aftermath of the terrorist attacks of Sept. 11, 2001. He is now the director of NIST’s Special Programs Office and its Chief Data Officer. Sunder is a recipient of the Presidential Rank Award of Distinguished Executive (2017), and the Gold Medal Award (2005) from the U.S. Department of Commerce, its highest honor, for distinguished leadership of the WTC investigation. Sunder was elected to the National Academy of Construction in 2012.

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Well done. Thank you for sharing, and for all your hard work to help others.

Did your team investigate whether toxic fumes were emitted by the burning of insulation on telecommunications wiring?

Did you test for the vibrational properties of the non- metallic components of the structures? The reason being that if there have been other heavy construction around those buildings before the collapse and the materials were not designed to withstand the vibrations from the nearby heavy construction machinery then there is the possibility of internal cracks in the non-metallic components . The plane hitting it just shook the material to fracture. I believe the same phenomenom was possible for the surfside collapse in Florida. There the need to redesign our cement and mortar.

Hi Mr Sunder I remember watching in horror as the tragic scene was displayed on TV, fortunately being in SA I was not impacted directly but can only imagine the terrible tragic especially after watching Netflix film recently with Nicholas Cage trapped underground. My question to you as a Force Metrologist and seeing various rumours or videos that their was more involved then what meets the eye, as in the speculation that the Towers could not simply collapse straight down and conspiracy theory's that the structural foundations where tampered with or even explosions set of at the precise time to weaken this , i would really like to know from someone like yourself is this was just propaganda or reality that everyone has ignored. I could not imagine where it to happen in Cape Town as it would be like a surreal nightmare and my heart goes out to everyone involved and families who lost there loved ones in the brave call of duty.

In reflecting back on my time at NIST, I often think of the work of you and your team on the WTC investigation as one of the most, if not the most, proud moments of just being affiliated with the Institute and the work carried out there. Your leadership was instrumental in the success of this monumental project. It was a very real and publicly tangible example of the important work done by NIST, which is often lost on the general public. And as you point out, it is less about simply understanding why this disaster happen in the manner that it did, but more importantly, what can we learn to improve our future developments and the safety and, in this case, resilience of existing and future building structures. That's where the real, true, and ironically immeasurable, impact of of NIST's work resides: in the disasters that didn't happen in the future.

Kevin Carr, former MEP Director

Thank you so much for your comments. As you so rightly observe, the real, true, and immeasurable impact of NIST's work on future developments and safety. As you know, this was a team effort with extensive engagement of all those affected by the horrific events and their consequences as well as the broader public.

Shyam Sunder, Lead Investigator

I noticed this article makes no mention of Architects and Engineers for 9/11 Truth. Will NIST disclose to the public the computer inputs of its mathematical models used for simulating how the buildings were destroyed? Thank you.

Henry, Thank you for your question. This information was exempt from public disclosure under Section 7d of the National Construction Safety Team Act because it was determined by the Director of NIST that release of the files might jeopardize public safety. The withheld information contains detailed connection models that have been validated against actual events, and therefore, provide tools that could be used to predict the collapse of a building. The information contained in the withheld files is sufficiently detailed that it might be used to develop plans to destroy other, similarly constructed, buildings.

In Michael Quick v. United States Department of Commerce, National Institute of Standards and Technology, Civil Action No. 09-02064 (CKK) U.S. District Court of the District of Columbia, Apr. 7, 2011, the court upheld NIST’s finding to withhold this information.

Thank you for your response, Mark. Is there a more complete version of the WTC 7 collapse simulation? The only simulation I have been able to review is the NIST WTC 7 collapse model where the building begins to bend and warp in on itself, but the simulation does not show the free fall speed as observed by witnesses and recorded on multiple news footage videos. Would NIST be willing to provide data inputs and mathematical models for just the free fall portion of the collapse after collapse initiation? I believe the collapse initiation is what is being guarded from the public, correct? Thanks again.

Please see #11 and #29 at https://www.nist.gov/topics/disaster-failure-studies/faqs-nist-wtc-7-in… for answers to your questions. All the public data we have available on our World Trade Center investigation is at https://www.nist.gov/topics/disaster-failure-studies/world-trade-center… .

Has NIST reached out to Richard Gage and the over 3400 architects and engineers petitioning for a new investigation for the collapse of the buildings? At least one of those members is a former NIST employee, Peter Michael Ketcham. They are willing to share their results after years of investigating the building destruction themselves and using data NIST has provided. Richard Gage does a frequent review of the WTC tower destruction with detailed information on YouTube - ae911truth. Please feel free to publicly refute those sessions as Mr. Gage's presentations seem to refute the each of NIST's findings. It seems unscientific and a bit shady to not address alternative destruction theories. The NIST FAQs seem to be in damage control mode rather than addressing some legitimate concerns that should be reviewed.

NIST is aware of other research related to the WTC collapse. We stand by our original findings.

But NIST's original findings are incorrect and have been shown by multiple institutions to be incomplete and error prone. You will not provide the input data or mathematical models to prove your findings so that makes NIST suspicious and research illegitimate. Your computer models and conclusions do not match observation. We can clearly see explosions traveling down both towers during the period of destruction. Why will NIST not allow the thousands of engineers, architects, and university professors to provide an alternate theory? We need a new investigation. The hubris for you all to congratulate each other is insulting.

In other words it was redacted.

Does the computer model that NIST produced match all the evidence observed? The NIST description seems to be far too complex. What does NIST have to say about all the reported molten steel and the measured temperatures of higher than 2000 F that lasted 6 weeks?

Thank you for your questions. You can find a summary of NIST's answers to these and other commonly asked questions at https://www.nist.gov/disaster-failure-studies/faqs-nist-wtc-towers-inve… and https://www.nist.gov/topics/disaster-failure-studies/faqs-nist-wtc-7-in… .

How are you dealing with the active lawsuit against your agency for arbitrary and capricious actions? You cannot hide from the truth forever. I look forward to the day that a grand jury reviews the mountains of evidence that support WTC1, 2 and 7 were all destroyed via controlled demolition, with thermite as the incendiary.

https://files.wtc7report.org/file/public-download/Complaint+AE+et+al+v+…

Dear Dr Shyam Sunder, I write this message from India. I had the honour to meet you at UL Conference sometime in 2008. The detailed investigation helped for us to also learn and update our codes back here at India as we revised the National Building Code in 2005 and 2016. We compliment and express gratitude to Team NIST for such extensive research and sharing. With good wishes.

Dear Mr. Sandeep Goel,

We are delighted to learn that NIST's WTC Investigation was helpful in updating the National Building Code of India. Thank you very much for sharing this information with us.

Dear Mr. S. Shyam Sunder et al., We all understand how different types of threats and coercion might impact human behavior and professional integrity. Despite all of that, we all should be able, in a time of self-reflection, to realize that truth is a liberating element in life. Especially once we get older and start seeing the world from a different, more mature perspective. We usually start thinking about our legacy and the side of good vs evil we took while inhabiting this planet. It must be very exhausting and "soul" killing to continue walking along the path someone had forced you to walk on a long time ago. It seems to me, that you have become more of a politician over the long years of your career at NIST. Your choice of words in the above article attests to it very clearly. Why don't you look inside of your "heart", think about everything again and do the right thing? You could help to transform this world into a better place for all of us. I can guarantee you that the tangible loses are significantly outweighed by the intangible ones!

Hi Dr Sunder,

I have a question regarding certain footnotes in the NCSTAR 1 report.

Footnotes 13 (Chapter 6 Reconstruction of the Collapses 6.1 APPROACH page 82) and 2 (Executive Summary E.3 SUMMARY OF FINDINGS page xxxvii) are similar with both outlining the overall focus of the NIST investigation and noting what the “Probable Collapse Sequence” refers to. The difference lies in the amount of focus, one noting none, the other noting little. To compare below, discarding the reference component and bracketing the different wording, firstly for 13 than 2 within the remaining body of text, highlights the alternate meanings.

The focus of the Investigation (does not actually include) the structural behavior of the tower after the conditions for collapse initiation were reached and collapse became inevitable.

The focus of the Investigation (includes little analysis of) the structural behavior of the tower after the conditions for collapse initiation were reached and collapse became inevitable.

Although both footnotes refer to the same thing, in light of 13 having been positioned within the main body of the report itself, it’s understood NIST only investigated factors leading to the initiation of collapses of the WTC towers, not the collapses themselves.

Taking into consideration:

1) Executive summaries are a concise version of and typically written after a report & 2) You stated in your Sep 2018 lecture (D-RED Speaker Series: How & Why the World Trade Center Collapsed) at Morgan State University, “There were two people who read every word in those reports, one was me the other was the lawyer.”

Why did you and the lawyer you mentioned choose to publish NCSTAR 1 with an alternate version of footnote 13 in the executive summary, otherwise known as footnote 2?

Hi Dr. Sunder,

I hope you’re well.

I have a question regarding Table P-1. Federal building and fire safety investigation of the WTC disaster as published in NCSTAR 1.

Considering the final report was written with the public in mind as a summary of what happened and how NIST addressed the issues with the sense that most members of the public likely won’t read any of the companion reports, why didn’t NIST detail that no steel was recovered from WTC 7 in the project purpose for the technical area of the Mechanical and Metallurgical Analysis of Structural Steel?

Dear Dr. Sunder, You remark justly that heat weakens steel and make a strong argument for collapse initiation. However, the steel of the as yet undestructed building was intact and not heated from kerosene doused office furniture fires. From the collapse time of both towers we can see a fairly constant acceleration at about two thirds of full free fall acceleration. This shows that the not-yet-collapsing part of the building must have been exerting a force of about one third of the weight of the collapsing top to lower its downwards acceleration. Newton’s third Law then tells us that the force that the collapsing top exerted on the as-yet-undestructed bottom part of the building must have also been a third of the collapsing top’s weight. Given that the towers were engineered to carry five times the weight of everything above at every floor, we have to wonder how it didn’t hold only one third of that weight. However, your team decided to stop investigating building performance at the point of collapse initiation, remarking global collapse became inevitable at that point. Given my argument, an investigation into the building performance during collapse would be worthwhile at some point into the future.

I'm curious to know how experts are able to tell that the two columns were from where the plane struck WTC 1.

There are a number of FAQs on the NIST website that address the columns. Here is a link: https://www.nist.gov/world-trade-center-investigation/study-faqs

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