World Trade Center
General information
Location	New York City, New York, U.S. (Lower Manhattan)
Destroyed	September 11, 2001 (September 11, 2001 attacks)
Owner	Port Authority of New York and New Jersey
Height
Antenna spire	1,727 ft (526.3 m) [1]
Roof	1,368 ft (417.0 m)
Top floor	1,355 ft (413.0 m)
Technical details
Floor area	8.6 million sq ft 800,000 m² (1 & 2)
Lifts/elevators	198 (1 & 2)
Design and construction
Architect(s)	Minoru Yamasaki, Emery Roth & Sons
Engineer	Leslie Robertson, Leslie E. Robertson Associates

The World Trade Center in New York City, United States, (sometimes informally referred to as the WTC or the Twin Towers) was a complex of seven buildings in Lower Manhattan, mostly designed by American architect Minoru Yamasaki and engineer Leslie Robertson and developed by the Port Authority of New York and New Jersey. It was initiated in 1960 by a Lower Manhattan Association created and chaired by David Rockefeller, who had the original idea of building the Center, with strong backing from the then-New York governor, his brother Nelson Rockefeller.^[2] The World Trade Center, New York, like most World Trade Centers located around the globe, belonged to the family of World Trade Centers Association. Larry Silverstein held the most recent lease to the complex, the Port Authority having leased it to him in July 2001.^[3] The complex, located in the heart of New York City's downtown financial district, contained 13.4 million square feet (1.24 million m²) of office space, almost four percent of Manhattan's entire office inventory at that time.^[4]

Best known for its iconic 110-story twin towers, the World Trade Center was beset by a fire on February 13, 1975 and a bombing on February 26, 1993. Despite the first two disasters, the World Trade Center was a part of New York City's identity and was recognized all over the world as an icon for the United States of America.

All of the original buildings in the complex were destroyed by Al-Qaeda in the September 11, 2001 attacks . One World Trade Center (1 WTC) and Two World Trade Center (2 WTC)—the North Tower and South Tower, respectively, collapsed, as did 7 World Trade Center (7 WTC).

The Marriott World Trade Center (3 WTC) was crushed by the collapses of 1 WTC and 2 WTC. 4 World Trade Center (4 WTC), 5 World Trade Center (5 WTC), and 6 World Trade Center (6 WTC) were damaged beyond repair and later demolished. In addition, St. Nicholas Greek Orthodox Church (not part of the complex) was destroyed by the collapse of 2 WTC; the Deutsche Bank Building was damaged beyond repair and is currently being deconstructed.

During the post-World War II period, the United States thrived economically, with increasing international trade. At the time, economic growth in New York City was concentrated in Midtown Manhattan, with Lower Manhattan left out. To help stimulate urban renewal, David Rockefeller, with support from his brother, New York Governor Nelson Rockefeller, suggested that the Port Authority should build a "world trade center" in Lower Manhattan.^[5] Initial plans, made public in 1961, identified a site along the East River for the World Trade Center.^[5] Objections to the plan came from New Jersey Governor Robert B. Meyner, who resented that New York would be getting this $335 million project.^[5] Meanwhile, New Jersey's Hudson and Manhattan Railroad (H&M) was facing bankruptcy. Port Authority executive director, Austin J. Tobin agreed to take over control of the H&M Railroad, in exchange for support from New Jersey for the World Trade Center project.^[5]

With this acquisition, the Port Authority would obtain the Hudson Terminal, and decrepit buildings located above the terminal in Lower Manhattan.^[5] The Port Authority decided to demolish these buildings, and use this site along the Hudson River for the World Trade Center.^[5] The towers in the complex were designed by architect Minoru Yamasaki with Antonio Brittiochi and Emery Roth & Sons as associate architects. The World Trade Center was one of the most striking American implementations of the architectural ethic of Le Corbusier, as well as the seminal expression of Yamasaki's gothic modernist tendencies.

Structural design

The World Trade Center included many structural engineering innovations in skyscraper design and construction. The towers were designed as framed tube structures. There was a frame of closely-spaced columns tied together by deep spandrel beams along the exterior perimeter. The interior had 47 columns, all concentrated in the core. Engineer Felix Samuely used a similar concept in his "Mullion wall" buildings in the early 1950s as did Eero Saarinen in his US Embassy, London (1955-60); but these projects were low to medium rise and may not have been influences.

The perimeter columns supported virtually all lateral loads, such as wind loads, and shared the gravity loads with the core columns.^[6] All columns were founded on bedrock, which unlike Midtown Manhattan, where the bedrock is shallow, is at 65 feet (20m) below the surface. Above the seventh floor there were 59 perimeter columns along each face of the building. The perimeter columns had a square cross section, 14 inches on a side (36 cm), and were constructed of welded steel plate.^[6] The thickness of the plates and grade of steel were varied over the height of the tower, ranging from 36 ksi to 100 ksi, with the steel strength and plate thickness decreasing with height.^[6] The perimeter structure was constructed with extensive use of prefabricated modular pieces, which consisted of three columns, three stories tall, connected together by spandrel plates. The spandrel plates were welded to the columns at the fabrication shop. The modular pieces were typically 52 inches (1.3 m) deep, and extended for two full floors and half of two more floors.^[6]

Adjacent modules were bolted together, with the splices occurring at mid-span of the columns and spandrels. The spandrel plates were located at each floor, and served to transmit shear flow between columns, thus allowing them to work together in resisting lateral loads. The joints between modules were staggered vertically, so the column splices between adjacent modules were not at the same floor.^[6]

The building's core housed the elevator and utility shafts, restrooms, three stairwells, and other support spaces. The core in 1 WTC was oriented with the long axis east to west, while that of 2 WTC was oriented north to south. The core of each tower was a rectangular area 87 by 135 feet (27 by 41 m) and contained 47 steel columns running from the bedrock to the top of the tower.^[6] The columns tapered with height, and consisted of welded box sections at lower floors and rolled wide-flange sections at upper floors. All of the elevators and stairwells were located in the core.

The large, column-free space between the perimeter and core was bridged by prefabricated floor trusses. The floors supported their own weight, as well as live loads, provided lateral stability to the exterior walls, and distributed wind loads among the exterior walls. The floors consisted of 4 inch (10 cm) thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors. The trusses had a span of 60 feet (18.2 m) in the long-span areas and 35 feet (11.0 m) in the short span area.^[6] The trusses connected to the perimeter at alternate columns, and were therefore on 6 foot 8 inch (2.03 m) centers. The top chords of the trusses were bolted to seats welded to the spandrels on the exterior side and a channel welded to the core columns on the interior side. The floors were connected to the perimeter spandel plates with vicsoelastic dampers, which helped reduce the amount of sway felt by building occupants. The trusses supported a 4-inch-thick (10 cm) lightweight concrete floor slab, with shear connections for composite action.^[6]

Hat trusses (or "outrigger truss") located from the 107th floor to the top of the buildings were designed to support a tall communications antenna on top of each building,^[6] though only 1 WTC (north tower) actually had an antenna. The truss system consisted of six trusses along the long axis of core and four along the short axis. This truss system allowed some load redistribution between the perimeter and core columns and supported the transmission tower.

Design innovations

To solve the problem of wind sway or vibration in the construction of the towers, chief engineer Leslie Robertson took a then unusual approach — instead of bracing the buildings corner-to-corner or using internal walls, the towers were essentially hollow steel tubes surrounding a strong central core. The 208 feet (63.4 m) wide facade was, in effect, a prefabricated steel lattice, with columns on 39 inch (100 cm) centers acting as wind bracing to resist all overturning forces; the central core took the majority of the gravity loads of the building. A very light, economical structure was built by keeping the wind bracing in the most efficient area, the outside surface of the building, thus not transferring the forces through the floor membrane to the core, as in most curtain-wall structures. The core supported the weight of the entire building and the outer shell containing 240 vertical steel columns called Vierendeel trusses around the outside of the building, which were bound to each other using ordinary steel trusses. In addition, 10,000 dampers were included in the structure. With a strong shell and core such as this, the exterior walls could be simply light steel and concrete. With the massive core and lightweight shell for structural integrity, Robertson created a tower that was extremely light for its size. This method of construction also meant that the twin towers had high load-bearing walls.

The buildings were also the second supertall buildings to use sky lobbies, after the John Hancock Center in Chicago.^[7] Skylobbies are floors where commuters can switch from an express elevator that goes only to the sky lobbies to a local elevator that goes to each floor in a section. The local elevators were stacked on top of each other, within the same elevator shaft. Located on the 44th and 78th floors of each tower, the sky lobbies enabled the elevators to be used efficiently while taking up a minimum of valuable office space.^[8] Altogether, the World Trade Center had 95 express and local elevators.^[9] This system was inspired by the New York City Subway system, whose lines include local stations where local trains stop and express stations where all trains stop.^[10]

The site of the World Trade Center was located on landfill, with the bedrock located 65 feet below.^[11] In order to construct the World Trade Center, it was necessary to build the "bathtub", with the slurry wall along the West Street side of the site, which serves the purpose of keeping water from the Hudson River out. The slurry method involves digging a trench, and as excavation proceeds, filling the space with a "slurry" mixture, composed of bentonite, which plugs holes and keeps water out. When the trench was dug out, a steel cage was inserted, with concrete poured in, forcing the "slurry" out. The "slurry" method was devised by the Port Authority's chief engineer, John M. Kyle, Jr.

Construction

Groundbreaking for the construction of the World Trade Center was on August 5, 1966.^[12] The construction was under the auspices of the semiautonomous Port Authority of New York and New Jersey. Thirteen square blocks of low rise buildings in Radio Row, some of which predated the American Civil War, were razed to clear the site for construction.

The excavation of the foundations of the WTC complex, known as the Bathtub, was particularly complicated since there were two subway tubes close by needing protection without service interruption. A six-level basement was built in the foundations. The excavation of about 1 million cubic yards (760,000 m³) of earth and rock created a $90 million real estate asset for the project owner, the Port Authority of New York and New Jersey, which helped offset the enormous loss in revenues which came from the tax breaks given to the Trade Center itself. The soil was used to create 23 acres (93,000 m²) of landfill in the Hudson River next to the World Trade Center site, which became the site of Battery Park City (still under development).

In 1970, construction was completed on One World Trade Center, with its first tenants moving into the building in December 1970. Tenants first moved into Two World Trade Center in January 1972.^[13] When the World Trade Center twin towers were completed, the total costs to the Port Authority had reached $900 million.^[14] The ribbon cutting ceremony was on April 4, 1973.^[15]

Architectural criticism

Although the towers became an undeniable icon of New York City, they were not without flaws and were handicapped in many ways. Initially conceived, (as the name suggests) as a complex dedicated to companies and organizations directly taking part in "world trade," they at first failed to attract the expected clientele. During the early years, various governmental organizations became key tenants of the World Trade Center, including the State of New York. It was not until the 1980s that the city's perilous financial state eased, after which an increasing number of private companies — mostly financial firms tied to Wall Street — became tenants.

Moreover, the trade center's "superblock", which replaced a more traditional, dense neighborhood, was regarded by some critics as an inhospitable environment that disrupted the complicated traffic network typical of Manhattan. For example, in his book The Pentagon of Power, the technical historian Lewis Mumford denounced the center as an "example of the purposeless giantism and technological exhibitionism that are now eviscerating the living tissue of every great city." On the other hand, Mr. Yamasaki saw the expanse as a focal point of serenity amidst the chaos of the city. The twin towers' narrow office windows, only 18 inches wide, were also disliked by many for impairing the view from the buildings.^[16] This design element reflected on Yamasaki's fear of heights and desire to make building occupants secure with narrow windows.^[16]

For many years, the immense Austin J. Tobin Plaza was unwelcoming, and often beset by brisk winds at the ground level.^[17] In 1999, the outdoor plaza reopened after undergoing $12 million renovations, which involved replacing marble pavers with gray and pink granite stones, adding new benches, planters, new restaurants and food kiosks, and outdoor dining areas.^[18] In later years, the plaza became a center for outdoor concerts and other activities.

The Twin Towers

Ultimately the complex came to consist of seven buildings, but its most notable features were the main twin towers. Each of the WTC towers had 110 stories. 1 WTC (the North Tower, which featured a massive 360-foot high TV antenna added in 1978) stood 1,368 feet (417 m) high,^[19] and 2 WTC (the South Tower, which contained the observation deck) was 1,362 feet (415 m) high.^[19] The length and breadth of the towers were 208 feet (63.4 m) x 208 feet (63.4 m). Although only Tower 1 featured an antenna, the structure of each building was designed to carry a broadcast mast, and in the basement of the complex, The Mall at the World Trade Center was Manhattan's largest mall until 9-11.

When completed in 1972, 1 WTC became the tallest building on Earth, unseating the Empire State Building after a 40 year reign. 2 WTC became the second tallest building in the world when completed in 1973. The difference in height between the two towers was because of a Port Authority request to have two floors, the 43rd and the 67th, in 1 WTC raised, the lower of the taller floors being a cafeteria for PANY workers.^{[citation needed]} 2 WTC did not need these facilities, so it remained 1,362 feet. Regardless, the WTC towers held the height record only briefly. As the building neared completion in 1973, work had already begun on Chicago's Sears Tower, which ultimately reached 1,450 feet (442 m).^[20] With the World Trade Center's destruction, the Empire State Building again became the tallest building in New York, after spending almost 30 years as the third-tallest in the city.

The towers' sheer size was the subject of a joke during a press conference unveiling the landmarks. Minoru Yamasaki was asked: "Why two 110-story buildings? Why not one 220-story building?" His response was: "I didn't want to lose the human scale". Another popular joke among New York urbanites that died out late in the 1970s from overtelling was that the towers looked like the boxes in which the Chrysler Building and Empire State Building were packaged.

Of the 110 stories, eight were set aside for technical services (mechanical floors) Level B6/B5, Floors 7/8, 41/42, 75/76 and 108/109, in four two-floor areas evenly spread up the building. All the remaining floors were free for open-plan offices. Each floor of the towers had 40,000 square feet of space for occupancy.^[9] Each tower had 3.8 million square feet (350,000 m²) of office space. Altogether the entire complex of seven buildings had 11.2 million square feet (1.04 km²) of space.

During the 1990s, approximately 500 companies had offices in the complex, including many financial companies such as Morgan Stanley, Aon Corporation, Salomon Brothers, as well as the Port Authority itself. Electrical service to the towers was supplied by Consolidated Edison (ConEd) at 13,800 volts. This service passed through the World Trade Center Primary Distribution Center (PDC) and sent up through the core of the building to electrical substations located on the mechanical floors. The substations "stepped" the 13,800 primary voltage down to 480/277 volt secondary power and further to 120/208 volt general power and lighting service. The complex also was served by emergency generators located in the sublevels of the towers and on the roof of 5 WTC.^[21][22]

The 110th Floor of 1 WTC (North Tower) housed commercial and public service radio & television transmission equipment. The roof of 1 WTC contained a vast array of transmission antennas, including the 360 ft (approx 110m) center antenna mast, which was rebuilt in 1999 by Dielectric Inc. to accommodate DTV. The center mast contained the television signals for almost all NYC television broadcasters: WCBS-TV 2, WNBC-TV 4, WNYW 5, WABC-TV 7, WWOR-TV 9 Secaucus, WPIX 11, WNET 13 Newark, WPXN-TV 31, and WNJU 47. It also had four NYC FM broadcasters on it as well: WPAT-FM 93.1, WNYC 93.9, WKCR 89.9, and WKTU 103.5.^[23] Access to the roof was controlled from the WTC Operations Control Center (OCC) located in the B1 level of 2 WTC.

The World Trade Center complex was protected by an extensive fire detection and voice evacuation paging system upgraded after the 1993 bombing. Fire Command Stations, staffed by Fire Safety Directors were located in the lobbies of each building and the Operations Control Center (OCC) monitored these systems. An extensive study of the performance of World Trade Center Fire Protection Systems was conducted by the National Institute of Standards and Technology (NIST) following 2001-09-11.^[24]

Observation deck and Windows on the World

Although most of the space in the WTC complex was off-limits to the general public, 2 WTC (South Tower) featured a public observation area named "Top Of The World." When visiting the observation deck, visitors would first pass through security checks added after the 1993 World Trade Center bombing. Next, visitors were whisked to the 107th floor indoor observatory at a height of 1,310 feet (399 m) and greeted with a 360 degree view of the New York City skyline, and exhibitions including a three-dimensional scale model of Manhattan, and a simulated helicopter ride around the city. Weather permitting, visitors could take two short escalator rides up from the 107th floor and visit what was the world's highest outdoor viewing platform. At a height of 1,377 feet (420 m), visitors were able to take in a view of the North Tower and New York City unlike any other. On a clear day, visitors could see up to 49 miles (78 km) in any given direction. An anti-suicide fence was placed on the roof itself, with the viewing platform set back and elevated above it, requiring only an ordinary railing and leaving the view unobstructed, unlike the observation deck of the Empire State Building.

The North Tower (1 WTC) had a restaurant on the 107th floor called Windows on the World, which was an elegant restaurant known as a place for big celebrations, such as weddings. In its last full year of operation, 2000, Windows on the World reported revenues of $37.5 million, making it the highest-grossing restaurant in the United States.

The other buildings

Five smaller buildings stood around the 16 acre (65,000 m²) block. One was the 22-floor Vista Hotel (3 WTC) at the southwest corner of the site, that was crushed between the two towers. Three low-rise buildings (4 WTC, 5 WTC, and 6 WTC) in the same hollow tube design as the towers also stood around the plaza. 6 World Trade Center, at the north west corner, housed the United States Customs Service and the U.S. Commodities Exchange. 5 World Trade Center was located at the northeast corner, above the PATH station, and 4 World Trade Center was at the southeast corner. In 1987, a 47-floor office building called 7 WTC was built north of the block. Beneath the World Trade Center complex was an underground shopping mall, which in turn had connections to various mass transit facilities, including the New York City Subway system and the Port Authority's own PATH trains connecting Manhattan to Jersey City, Hoboken, and Newark.

One of the world's largest gold depositories was stored underneath the World Trade Center, owned by a group of commercial banks. The 1993 bomb detonated close to the vault, but it withstood the explosion, as did the towers. Seven weeks after the September 11th attacks, $230 million in precious metals were removed from basement vaults of 4 WTC, which included 3,800 100-Troy-ounce registered gold bars and 30,000 1,000-ounce silver bars.^[25]

On a typical weekday 50,000 people worked in the towers,^[9] with another 200,000 passing through as visitors. The complex was so large that it had its own zip code, 10048. The towers offered spectacular views from the observation deck (located on top of the South Tower) and the Windows on the World restaurant (located on top of the North Tower). The Twin Towers became known worldwide, appearing in movies, TV shows, postcards, merchandise, magazines and much more, and became a New York icon, such as the Empire State Building, or Statue of Liberty. French high wire acrobatic performer Philippe Petit walked between the towers on a tightrope in 1974, and Brooklyn toymaker George Willig scaled the south tower in 1977.

February 13, 1975 fire

On February 13, 1975, the WTC North Tower was beset by a fire which spread over nearly half of the 11th floor. The fire spread to other floors through openings in the floor slabs which were used to carry phone wires. The fires on other floors were extinguished almost immediately, and the main fire was put out in a few hours. Fireproofing protected the steel from melting and there was no structural damage to the tower. This event led to the installation of a sprinkler system in both towers. Firefighters claim that had the sprinklers been installed when the tower was built, the fire probably would not have spread as much as it did. Other than the damage caused by the fire, a few floors below suffered water damage from the extinguishing of the fires above.

Bombing of February 26, 1993

On February 26, 1993 at 12:17 PM, a Ryder truck filled with 1,500 pounds (680 kg) of explosives was planted by Ramzi Yousef and detonated in the underground garage of the North Tower, opening a 100 foot (30 m) hole through 5 sublevels of concrete leaving six people dead and 50,000 other workers and visitors gasping for air in the shafts of the 110 story towers.

Many people inside the North Tower were forced to walk down darkened stairwells which contained no emergency lighting, some taking two hours or more to reach safety. As the Port Authority was a bistate agency, the towers were exempt from New York City building codes. Subsequent to the bombing The Port Authority installed emergency lighting in the stairwells. It is believed that this lighting saved many lives during the events of September 11, 2001.

In 1997 and 1998, six Islamist extremists were convicted and sentenced to life in prison for their roles in the bombing. According to a presiding judge, the conspirators' chief aim at the time of the attack was to destabilize the north tower and send it crashing into the south tower, toppling both landmarks.

As a memorial to the victims of the bombing of the tower, a reflecting pool was installed with the names of those who had been killed in the blast. Following the September 11, 2001 attacks, relief workers found a single fractured piece of the fountain etched with the word "John"; to date it is the only remaining part of the 1993 memorial that survived the collapse of the towers.

Lease

In 1998, plans were approved by the Port Authority to privatize the World Trade Center.^[26] In 2001, the Port Authority sought to lease the World Trade Center to a private entity. Bids for the lease came from Vornado Realty Trust, a joint bid between Brookfield Properties Corporation and Boston Properties,^[27] and a joint bid by Silverstein Properties and The Westfield Group.^[28] By privatizing the World Trade Center, it would be added to the city's tax rolls.^[28] The lease was also intended to raise funds for other Port Authority projects.^[29] On February 15, 2001, the Port Authority announced that Vornado Trust Realty had won the lease for the World Trade Center, paying $3.25 billion for the 99-year lease.^[30] Vornado Realty outbid Silverstein by $600 million, though Silverstein upped his offer to $3.22 billion. However, Vornado insisted on last minute changes to the deal, including a shorter 39-year lease, which the Port Authority considered nonnegotiable.^[31] Vornado later withdrew and Silverstein's bid for the lease to the World Trade Center was accepted on April 26 2001,^[32] and closed on July 24, 2001.^[33]

September 11, 2001

On September 11 2001 at 8:46 a.m. Eastern Time, Al Qaeda suicide hijackers crashed American Airlines Flight 11 into the northern facade of the North Tower.^[34][35] Seventeen minutes later, at 9:03 a.m., a second team of hijackers crashed United Airlines Flight 175 into the South Tower,^[35][36] which collapsed and disintegrated at 9:59 a.m. At 10:28 a.m., the North Tower collapsed and disintegrated. At 5:20 p.m., 7 World Trade Center collapsed. The four remaining buildings in the WTC plaza sustained heavy damage from debris, and were ultimately demolished.

At the time of the incident, media reports suggested that tens of thousands might have been killed in the massacre, as on any given day upwards of 50,000 people could be inside the towers. Ultimately, 2,750 ^[37] death certificates were filed relating to the 9/11 attacks, as of May 23, 2007. Of these, 1,614 (59%) were identified from recovered physical remains. 340 Emergency personnel and 60 police officers were killed in the collapse of the Twin Towers. Morgan Stanley was the largest tenant in the World Trade Center, with approximately 2,500 employees in the South Tower and 1,000 in the North Tower.^[38] For the following 8½ months, the World Trade Center site cleanup and recovery continued 24 hours a day and involved thousands of workers. The massive pile of debris smoked and smoldered for 99 days.

The World Trade Center was an American icon and has been featured in numerous films, as well as appearing in many television shows, cartoons, comic books, computer/video games and music videos. The Twin Towers have appeared in popular television shows such as Friends, Sex and the City, The Simpsons and Family Guy. The Twin Towers have also appeared prominently in popular films such as Three Days of the Condor, Escape From New York, Godspell, the 1976 King Kong, Home Alone 2: Lost in New York, Armageddon, and Artificial Intelligence (A.I.). The Towers have also been featured in music videos by popular american artists such as The Spice Girls, Madonna, Blondie, and Linkin Park.

The events surrounding September 11 are portrayed in several documentaries and movies, including two major motion pictures made in 2006, Oliver Stone's World Trade Center and Paul Greengrass' United 93. Several movies released shortly after 9/11 digitally erased the Twin Towers from skyline shots. As of 2007 most reruns of popular television shows have chosen to leave the Twin Towers in airings of the show such as cut scenes in Friends and episodes of The Simpsons.

In his novel, Underworld (1997), Don DeLillo cites the Towers on several occasions, once even having his protagonist ponder the metaphysical (prescient and eerie) connection between the Towers and the Fresh Kills landfill on Staten Island (where the debris from the WTC site was taken). In Part 4 of the novel, however, subtitled "Summer 1974," the Center is described as still being under construction.

Template:Future building

The Lower Manhattan Development Corporation, the agency charged with coordinating the reconstruction of the World Trade Center site, selected the master plan, Memory Foundations by Daniel Libeskind,^[39] which includes the 1,776 ft (541 m) Freedom Tower. The height of 1,776 feet (541 m) was chosen as a reference to the year of American independence. A new 7 World Trade Center office building, which was not part of the site master plan, officially opened on May 23, 2006.

The Lower Manhattan Development Corporation sponsored the World Trade Center Site Memorial Competition, an international design competition for the World Trade Center Memorial in spring 2003. The winning design, Michael Arad and Peter Walker's Reflecting Absence, was chosen in January 2004.

The World Trade Center name will continue to be used as name of the site, as will the New York City Subway and PATH train stations that serve the complex. A temporary PATH station, largely following the layout of the original, is the first part of the complex to have reopened.

On November 22, 2004, New York Governor George Pataki named the living former presidents as honorary members of the board rebuilding the World Trade Center.

On May 18, 2005, Donald Trump, long-time opponent of the Freedom Tower, proposed the Twin Towers II plan to rebuild the Twin Towers with various safety, structural, and technological improvements.

On June 29, 2005, a redesigned Freedom Tower was unveiled which more closely resembled the character of the fallen towers. The new design also boasted several safety improvements over previous proposals.

On December 15, 2005, Sir Norman Foster was announced as the architect who will design the second of five new office towers planned for the site.

On March 13, 2006 workers arrived at the World Trade Center site to remove remaining debris and start surveying work. This marks the official start of construction of the WTC Memorial and Museum.^[40]

In April 2006, a tentative agreement was reached by the owner of the site, The Port Authority, and private developer Larry Silverstein. The main elements of that agreement are that Silverstein ceded rights to develop the Freedom Tower and Tower Five in exchange for financing with Liberty Bonds for Tower Two, Three, and Four which are considered to be the most marketable properties of the site. On April 27, 2006, a groundbreaking ceremony was held for the Freedom Tower.^[41]

In May 2006, architects Richard Rogers and Fumihiko Maki were announced as the architects for Towers Three and Four, respectively.

The final designs for Towers Two, Three and Four were unveiled on September 7, 2006. Tower Two, or 200 Greenwich Street, will have a roof height of 1,254 feet (382 m) and a 96-foot (29 m) tripod spire for a total of 1,350 feet (411 m). Tower Three, or 175 Greenwich Street will have a roof height of 1,155 feet (352 m) and an antennae height of 1,255 feet (383 m). Tower Four, or 150 Greenwich Street, will have an overall height of 946 feet (288 m).^[42]

As of late 2006, work at the World Trade Center site continued. Foundation work has started on the Freedom Tower, Calatrava Hub, and the memorials. By the end of 2006, the site was expected to look like the massive construction project that built the previous World Trade Center.

On June 22, 2007 the Port Authority of New York and New Jersey announced that JP Morgan Chase will build Tower 5, a 42 story building on Site 5 currently occupied by the Deutsche Bank Building. ^[43] Kohn Pedersen Fox was officially chosen as the architect for the building on July 17, 2007^[44]

• World Trade Center official site
• WorldTrade Center.com - The global online tribute
• Victims of the World Trade Center Collapse - neverforget911.org
• World Trade Center - 1970-2001 Photo Retrospective
• Archived version of Top Of The World Trade Center Observatories website
• World Trade Center Memorial Foundation
• Skyscraper Museum WTC Dossier
• Emporis — Special Coverage of the World Trade Center in New York City
• Lower Manhattan Development Corporation
• LowerManhattan.Info Official site for Lower Manhattan Construction Command Center.
• The Mega WTC Picture Thread at Skyscraper City
• Completing the Vision: Video unveiling the 4 towers to be erected on the World Trade Center site (Giroud Pichot 09-07-06)
• Building the World Trade Center, a 1983 documentary about the construction of the WTC by the Port Authority of New York and New Jersey-from Google Video
• Video of cornerstone laying ceremony for the Freedom Tower on July 4, 2004
• DMOZ directory
• New design for New York’s WTC. Renders.

Webcams

• Project Rebirth
• World Trade Center Site / Ground Zero Webcams

40°42′42″N 74°00′45″W / 40.71167°N 74.01250°W / 40.71167; -74.01250

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