Twin tower

World Trade Center (1973–2001)

The original World Trade Center was a large complex of seven buildings in Lower ManhattanNew York City, United States. It featured the landmark Twin Towers, which opened on April 4, 1973, and were destroyed in 2001 during the September 11 attacks. At the time of their completion, the Twin Towers—the original 1 World Trade Center, at 1,368 feet (417 m); and 2 World Trade Center, at 1,362 feet (415.1 m)—were the tallest buildings in the world. Other buildings in the complex included the Marriott World Trade Center (3 WTC), 4 WTC5 WTC6 WTC, and 7 WTC. The complex was located in New York City's Financial District and contained 13,400,000 square feet (1,240,000 m2) of office space.[4][5]
World Trade Center
World Trade Center, New York City - aerial view (March 2001).jpg
The original World Trade Center in March 2001. The tower on the left, with antenna spire, was1 WTC. The tower on the right was 2 WTC. All seven buildings of the WTC complex are partially visible; refer to map below. The red granite-clad building left of the Twin Towers was the original7 World Trade Center. In the background is theEast River.
World Trade Center (1973–2001) is located in Lower Manhattan
World Trade Center (1973–2001)
Location within Lower Manhattan
Record height
Tallest in the world from 1971 to 1973[I]
Preceded byEmpire State Building
Surpassed byWillis Tower
General information
StatusDestroyed
LocationLower ManhattanNew York City
Coordinates40°42′42″N74°00′45″W
GroundbreakingAugust 5, 1966; 51 years ago
Construction started
  • 1 WTC: August 1968
  • 2 WTC: January 1969
  • 3 WTC: December 1979
  • 4, 5, and 6 WTC: 1970
  • 7 WTC: 1983
Completed
  • 1 WTC: December 23, 1970
  • 2 WTC: July 19, 1971
  • 3 WTC: July 1981
  • 4, 5, and 6 WTC: 1975
  • 7 WTC: May 1987[1]
OpeningApril 4, 1973; 45 years ago
DestroyedSeptember 11, 2001; 16 years ago
Owner
Other information
Height
Antenna spire1 WTC: 1,728 feet (526.7 m)
Roof
  • 1 WTC: 1,368 feet (417 m)
  • 2 WTC: 1,362 feet (415.1 m)
  • 3 WTC: 250 feet (76.2 m)
  • 4 and 5 WTC: 120 feet (36.6 m)
  • 6 WTC: 110 feet (33.5 m)
  • 7 WTC: 610 feet (185.9 m)
Top floor
  • 1 WTC: 1,355 feet (413 m)
  • 2 WTC: 1,348 ft (411 m)
Technical details
Floor count
  • 1 and 2 WTC: 110 floors
  • 3 WTC: 22 floors
  • 4 and 5 WTC: 9 floors
  • 6 WTC: 8 floors
  • 7 WTC: 47 floors
Floor area
  • 1 and 2 WTC: 4,300,000 sq ft (400,000 m2) each
  • 45, and 6 WTC: 500,000 sq ft (50,000 m2) each
  • 7 WTC: 1,868,000 sq ft (170,000 m2)
Lifts/elevators1 and 2 WTC: 99 each
Design and construction
Architect
Developer
EngineerWorthington, Skilling, Helle & Jackson,[2]Leslie E. Robertson Associates
Main contractorTishman Realty & Construction Company
References
I. ^ World Trade Center at Emporis
[3]
The core of the complex was built between 1975 and 1985, with a cost of $400 million (equivalent to $1.86 billion in 2016).[6] The World Trade Center experienced a fire onFebruary 13, 1975,[7] a bombing onFebruary 26, 1993,[8] and a bank robbery onJanuary 14, 1998.[9] In 1998, the Port Authority decided to privatize the World Trade Center, leasing the buildings to a private company to manage, and awarded the lease to Silverstein Properties in July 2001.[10]
On the morning of September 11, 2001, Al-Qaeda-affiliated hijackers flew two Boeing 767 jets into the North and South Towers within minutes of each other; two hours later, both had collapsed. The attacks killed 2,606 people in and within the vicinity of the towers, as well as all 157 on board the two aircraft.[11]Falling debris from the towers, combined with fires that the debris initiated in several surrounding buildings, led to the partial or complete collapse of all the buildings in the complex and caused catastrophic damage to ten other large structures in the surrounding area.
The cleanup and recovery process at theWorld Trade Center site took eight months, during which the remains of the other buildings were demolished. The World Trade Center complex was rebuilt over more than a decade. The site is being rebuilt with six new skyscrapers, while a memorial to those killed in the attacks and a new rapid transit hubhave both opened. One World Trade Center, the tallest building in the United States, is the lead building for the new complex, reaching more than 100 stories upon completion in November 2014.

Before the World Trade Center

The western portion of the World Trade Center site was originally under the Hudson River, with the shoreline in the vicinity of Greenwich Street. It was on this shoreline close to the intersection of Greenwich and the former Dey Street that Dutch explorer Adriaen Block's ship, the Tyger, burned to the waterline in November 1613, stranding Block and his crew and forcing them to overwinter on the island. They built the first European settlement in Manhattan. The remains of the ship were buried under landfill when the shoreline was extended starting in 1797, and were discovered during excavation work in 1916. The remains of a second ship from the eighteenth century were discovered in 2010 during excavation work at the site. The ship, believed to be a Hudson River sloop, was found just south of where the Twin Towers used to stand, about 20 feet below the surface.[12]
Later, the area became Radio Row. New York City's Radio Row, which existed from 1921 to 1966, was a warehouse district on the Lower West Side in the Financial District. Harry Schneck opened City Radio on Cortlandt Street in 1921, and eventually the area held several blocks of electronics stores, with Cortlandt Street as its central axis. The used radios, war surplus electronics (e.g., ARC-5radios), junk, and parts often piled so high they would spill out onto the street, attracting collectors and scroungers. According to a business writer, it also was the origin of the electronic component distribution business.[13]
The idea of establishing a World Trade Center in New York City was first proposed in 1943. The New York State Legislature passed a bill authorizing New York Governor Thomas E. Dewey to begin developing plans for the project[14] but the plans were put on hold in 1949.[15] During the late 1940s and 1950s, economic growth in New York City was concentrated in Midtown Manhattan. To help stimulate urban renewal in Lower Manhattan,David Rockefeller suggested that the Port Authority build a World Trade Center in Lower Manhattan.[16]
Plans for the use of eminent domain to remove the shops in Radio Row bounded byVeseyChurchLiberty, and West Streets began in 1961 when the Port Authority of New York and New Jersey was deciding to build the world's first world trade center. They had two choices: the east side of Lower Manhattan, near the South Street Seaport; and the west side, near the H&M station, Hudson Terminal.[17] Initial plans, made public in 1961, identified a site along the East River for the World Trade Center.[18] As a bi-state agency, the Port Authority required approval for new projects from the governors of both New Yorkand New Jersey. New Jersey Governor Robert B. Meyner objected to New York getting a $335 million project.[19] Toward the end of 1961, negotiations with outgoing New Jersey Governor Meyner reached a stalemate.[20]
 
The Radio Row in 1936, with theCortlandt Street station in the background, as seen in a photograph by Berenice Abbott
At the time, ridership on New Jersey's Hudson and Manhattan Railroad (H&M) had declined substantially from a high of 113 million riders in 1927 to 26 million in 1958 after new automobile tunnels and bridges had opened across the Hudson River.[21] In aDecember 1961 meeting between Port Authority director Austin J. Tobin and newly elected New Jersey Governor Richard J. Hughes, the Port Authority offered to take over the Hudson & Manhattan Railroad. The Port Authority also decided to move the World Trade Center project to the Hudson Terminalbuilding site on the west side of Lower Manhattan, a more convenient location for New Jersey commuters arriving via PATH.[20]With the new location and Port Authority acquisition of the H&M Railroad, New Jersey agreed to support the World Trade Center project.[22] As part of the deal, the Port Authority renamed the H&M "Port Authority Trans-Hudson", or PATH for short.[23]
In compensation for Radio Row business owners' displacement, the PANYNJ gave each business $3,000 each, without regard to how long the business had been there or how prosperous the business was.[24] After the area had been purchased for the World Trade Center in March 1964,[25] Radio Row was demolished starting in March 1965.[26] It was completely demolished by 1966.[27]
Approval was also needed from New York City Mayor John Lindsay and the New York City Council. Disagreements with the city centered on tax issues. On August 3, 1966, an agreement was reached that the Port Authority would make annual payments to the City in lieu of taxes for the portion of the World Trade Center leased to private tenants.[28] In subsequent years, the payments would rise as the real estate tax rate increased.[29]

Design and construction

Design

A typical floor layout and elevator arrangement of the WTC towers.
(video) The World Trade Center in the 1970s, including scenes of its construction.
On September 20, 1962, the Port Authority announced the selection of Minoru Yamasakias lead architect and Emery Roth & Sons as associate architects.[30] Yamasaki devised the plan to incorporate twin towers; Yamasaki's original plan called for the towers to be 80 stories tall,[31] but to meet the Port Authority's requirement for 10,000,000 square feet (930,000 m2) of office space, the buildings would each have to be 110 stories tall.[32]
Yamasaki's design for the World Trade Center, unveiled to the public on January 18, 1964, called for a square plan approximately 208 feet (63 m) in dimension on each side.[31][33]The buildings were designed with narrow office windows 18 inches (46 cm) wide, which reflected Yamasaki's fear of heights as well as his desire to make building occupants feel secure.[34] Yamasaki's design included building facades sheathed in aluminum-alloy.[35] The World Trade Center was one of the most-striking American implementations of the architectural ethic of Le Corbusier, and it was the seminal expression of Yamasaki's gothic modernist tendencies.[36]
A major limiting factor in building height is the issue of elevators; the taller the building, the more elevators are needed to service the building, requiring more space-consuming elevator banks.[32] Yamasaki and the engineers decided to use a new system with two "sky lobbies"—floors where people could switch from a large-capacity express elevator to a local elevator that goes to each floor in a section. This system, inspired by the local-express train operation that New York City's subway system used,[37] allowed the design to stack local elevators 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, increasing the amount of usable space on each floor from 62 to 75 percent by reducing the number of elevator shafts.[38] Altogether, the World Trade Center had 95 express and local elevators.[39]
The structural engineering firm Worthington, Skilling, Helle & Jackson worked to implement Yamasaki's design, developing the tube-frame structural system used in the twin towers. The Port Authority's Engineering Department served as foundation engineers, Joseph R. Loring & Associates as electrical engineers, and Jaros, Baum & Bolles (JB&B) asmechanical engineersTishman Realty & Construction Company was the general contractor on the World Trade Center project.Guy F. Tozzoli, director of the World Trade Department at the Port Authority, and Rino M. Monti, the Port Authority's Chief Engineer, oversaw the project.[40] As an interstate agency, the Port Authority was not subject to local laws and regulations of the City of New York, including building codes. Nonetheless, the structural engineers of the World Trade Center ended up following draft versions of the new 1968 building codes.[41]
The tube-frame design, earlier introduced byFazlur Khan, was a new approach that allowed more open floor plans than the traditional design that distributed columns throughout the interior to support building loads. The World Trade Center towers used high-strength, load-bearing perimeter steel columns called Vierendeel trusses that were spaced closely together to form a strong, rigid wall structure, supporting virtually all lateral loads such as wind loads, and sharing the gravity load with the core columns. The perimeter structure containing 59 columns per side was constructed with extensive use of prefabricated modular pieces, each consisting of three columns, three stories tall, connected by spandrel plates.[42] The spandrel plates were welded to the columns to create the modular pieces off-site at the fabrication shop.[43] 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, transmitting shear stress between columns, allowing them to work together in resisting lateral loads. The joints between modules were staggered vertically, so that the column splices between adjacent modules were not at the same floor.[41]
The core of the towers housed the elevator and utility shafts, restrooms, three stairwells, and other support spaces. 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. 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, providing lateral stability to the exterior walls and distributing wind loads among the exterior walls.[44] The floors consisted of 4 inches (10 cm) thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors.[42] The trusses connected to the perimeter at alternate columns and were 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 spandrel plates with viscoelastic dampers that helped reduce the amount of sway felt by building occupants.
Hat trusses (or "outrigger truss") located from the 107th floor to the top of the buildings were designed to support a tall communication antenna on top of each building.[42] Only 1 WTC (north tower) actually had an antenna fitted; it was added in 1978.[45] The truss system consisted of six trusses along the long axis of the 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.[42]
The tube frame design, using steel core and perimeter columns protected with sprayed-on fire resistant material, created a relatively lightweight structure that would sway more in response to the wind compared to traditional structures, such as the Empire State Buildingthat have thick, heavy masonry forfireproofing of steel structural elements.[46]During the design process, wind tunnel tests were done to establish design wind pressures that the World Trade Center towers could be subjected to and structural response to those forces.[47] Experiments also were done to evaluate how much sway occupants could comfortably tolerate; however, many subjects experienced dizziness and other ill effects.[48]One of the chief engineers Leslie Robertsonworked with Canadian engineer Alan G. Davenport to develop viscoelastic dampers to absorb some of the sway. These viscoelastic dampers, used throughout the structures at the joints between floor trusses and perimeter columns along with some other structural modifications, reduced the building sway to an acceptable level.[49]

Construction

 
World Trade Center under construction in May 1971
In March 1965, the Port Authority began acquiring property at the World Trade Center site.[25] Demolition work began on March 21, 1966, to clear thirteen square blocks of low rise buildings in Radio Row for construction of the World Trade Center.[26] Groundbreaking for the construction of the World Trade Center took place on August 5, 1966.[50]
The site of the World Trade Center was located on landfill with the bedrock located 65 feet (20 m) below.[51] To construct the World Trade Center, it was necessary to build a "bathtub" with a slurry wall around the West Street side of the site, to keep water from the Hudson River out.[52] The slurry method selected by Port Authority's chief engineer, John M. Kyle, Jr., involved digging a trench, and as excavation proceeded, filling the space with a "slurry" mixture composed of bentoniteand water, which plugged holes and kept groundwater out. When the trench was dug out, a steel cage was inserted and concrete was poured in, forcing the "slurry" out. It took fourteen months for the slurry wall to be completed. It was necessary before excavation of material from the interior of the site could begin.[53] The 1,200,000 cubic yards (920,000 m3) of material excavated were used (along with other fill and dredge material) to expand the Manhattan shoreline across West Street to form Battery Park City.[54][55]
In January 1967, the Port Authority awarded $74 million in contracts to various steel suppliers.[56] Construction work began on the North Tower in August 1968, and construction on the South Tower was under way byJanuary 1969.[57] The original Hudson Tubes, which carried PATH trains into Hudson Terminal, remained in service during the construction process until 1971, when a new station opened.[58] The topping out ceremony of 1 WTC (North Tower) took place onDecember 23, 1970, while 2 WTC's ceremony (South Tower) occurred later on July 19, 1971.[57] The first tenants moved into the North Tower on December 15, 1970,[1] while the South Tower started accepting tenants inJanuary 1972.[59] When the World Trade Center twin towers were completed, the total costs to the Port Authority had reached $900 million.[60] The ribbon cutting ceremony was on April 4, 1973.[61]
In addition to the twin towers, the plan for the World Trade Center complex included four other low-rise buildings, which were built in the early 1970s. The 47-story 7 World Trade Center building was added in the 1980s, to the north of the main complex. Altogether, the main World Trade Center complex occupied a 16-acre (65,000 m2superblock.[62][63]

Criticism

 
The WTC site building arrangement
Plans to build the World Trade Center were controversial. The site for the World Trade Center was the location of Radio Row, home to hundreds of commercial and industrial tenants, property owners, small businesses, and approximately 100 residents, many of whom fiercely resisted forced relocation.[64] A group of small businesses affected sought aninjunction challenging the Port Authority's power of eminent domain.[65] The case made its way through the court system to the United States Supreme Court; the Court refused to accept the case.[66]
Private real estate developers and members of the Real Estate Board of New York, led by Empire State Building owner Lawrence A. Wien, expressed concerns about this much "subsidized" office space going on the open market, competing with the private sector when there was already a glut of vacancies.[67][68] The World Trade Center itself was not rented out completely until after 1979 and then only due to the fact that the complex's subsidy by the Port Authority made rents charged for its office space relatively cheaper than that of comparable office space in other buildings.[69] Others questioned whether the Port Authority should have taken on a project described by some as a "mistaken social priority".[70]
The World Trade Center design brought criticism of its aesthetics from the American Institute of Architects and other groups.[35][71]Lewis Mumford, author of The City in Historyand other works on urban planning, criticized the project and described it and other new skyscrapers as "just glass-and-metal filing cabinets".[72] The Twin Towers were described as looking similar to "the boxes that theEmpire State Building and the Chrysler Building came in".[73] The twin towers' narrow office windows, only 18 inches (46 cm) wide and framed by pillars that restricted views on each side to narrow slots, were disliked by many.[34] Activist and sociologist Jane Jacobsalso criticized plans for the WTC's construction, arguing that the waterfront should be kept open for New Yorkers to enjoy.[74]
The trade center's "superblock", replacing 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, 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".[63]
In 1982, the immense plaza between the twin towers was renamed after the Port Authority's late chairman, Austin J. Tobin.[75] During the summer, the Port Authority installed a portable stage within Tobin Plaza for performers.[76] For many years, the Austin J. Tobin Plaza was often beset by brisk winds at ground level owing to the Venturi effectbetween the two towers.[77] In fact, some gusts were so high that pedestrian travel had to be aided by ropes.[78] In 1999, the outdoor plaza reopened after undergoing $12 million renovations, which involved replacing marblepavers with gray and pink granite stones, adding new benches, planters, new restaurants, food kiosks and outdoor dining areas.[79]

Complex

On a typical weekday 50,000 people worked in the towers[80] with another 200,000 passing through as visitors.[81] The complex was so large that it had its own zip code: 10048.[82]The towers offered expansive views from the observation deck atop the South Tower and the Windows on the World restaurant on top of the North Tower. The Twin Towers became known worldwide, appearing in numerous movies and television shows as well as on postcards and other merchandise, and became seen as a New York icon, in the same league as the Empire State Building, Chrysler Building and the Statue of Liberty.[83] The World Trade Center was compared toRockefeller Center, which David Rockefeller's brother Nelson had developed in midtown Manhattan.[84]

North and South Towers

Lobby of Tower 1, looking south along the east side of the building, August 19, 2000.
One World Trade Center and Two World Trade Center, commonly the Twin Towers, the idea of which was brought up by Minoru Yamasaki, were designed as framed tube structures, which provided tenants with open floor plans, uninterrupted by columns or walls.[85][86] They were the main buildings of the World Trade Center.[57] The North Tower (One World Trade Center), the tallest building in the world at 1,368 feet (417 m) by the time of its completion, began construction in 1966 with the South Tower (2 World Trade Center);[87]extensive use of prefabricated components helped to speed up the construction process, and the first tenants moved into the North Tower in December 1970, while it was still under construction.[88] When completed in 1973, the South Tower, Two World Trade Center (the South Tower) became the second tallest building in the world at 1,362 feet (415 m); the South Tower's rooftop observation deck was 1,362 ft (415 m) high and its indoor observation deck was 1,310 ft (400 m) high.[89] Each tower stood over 1,350 feet (410 m) high, and occupied about 1 acre (4,000 m2) of the total 16 acres (65,000 m2) ofthe site's land. During a press conference in 1973, Yamasaki was asked, "Why two 110-story buildings? Why not one 220-story building?" His tongue-in-cheek response was: "I didn't want to lose the human scale."[90]
 
South Tower lobby interior, overlooking the elevator core and red carpet from the balcony, October 1988.
When completed in 1972, 1 World Trade Center became the tallest building in the world for two years, surpassing the Empire State Building after a 40-year reign. The North Tower stood 1,368 feet (417 m) tall and featured a telecommunications antenna or mast that was added at the top of the roof in 1978 and stood 362 feet (110 m) tall. With the 362-foot (110 m)-tall antenna/mast, the highest point of the North Tower reached 1,730 feet (530 m).[89] Chicago's Sears Tower, finished in May 1973, reached 1,450 feet (440 m) at the rooftop.[91] Throughout their existence, the WTC towers had more floors(at 110) than any other building.[89] This number was not surpassed until the advent of the Burj Khalifa, which opened in 2010.[92][93]Each tower had a total mass of around 500,000 tons.[94]

Top of the World observation deck

 
Visitors on the viewing platform on the South Tower's roof, looking north toward Midtown Manhattan
Although most of the space in the World Trade Center complex was off-limits to the public, the South Tower featured two public viewing areas called Top of the World Trade Center Observatories: an indoor one on the 107th floor and an outdoor one on the roof. Visitors would pass through security checks added after the 1993 World Trade Center bombing,[95] then were sent to the 107th-floor indoor observatory at a height of 1,310 feet (400 m). The exterior columns on each side of the floor were narrowed to allow 28 inches of window width between them. The Port Authority renovated the observatory in 1995, then leased it to Ogden Entertainment to operate. Attractions added to the observation deck included a simulated helicopter ride around the city. The 107th-floor food court was designed with a subway car theme and featured Sbarro and Nathan's Famous Hot Dogs.[96][97] Weather permitting, visitors could ride two short escalators up from the 107th-floor viewing area to an outdoor platform at a height of 1,377 ft (420 m).[98] On a clear day, visitors could see up to 50 miles (80 km).[96]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.[97]

Windows on the World restaurant

 
Windows on the World restaurant interior, November 4, 1999
The North Tower had a restaurant on its 106th and 107th floors called Windows on the World, which opened in April 1976. The restaurant was developed by Joe Baum at a cost of more than $17 million.[99] Aside from the main restaurant, two offshoots were located at the top of the North Tower: "Hors d'Oeuvrerie" (offered a Danish smorgasbordduring the day and sushi in the evening) and "Cellar in the Sky" (a small wine bar).[100]Windows on the World also had a wine school program run by Kevin Zraly, who published a book on the course.[101]
Windows on the World was closed following the 1993 World Trade Center bombing.[99]Upon reopening in 1996, Hors d'Oeuvrerie and Cellar in the Sky were replaced with the "Greatest Bar on Earth" and "Wild Blue".[100] In 2000, its last full year of operation, Windows on the World reported revenues of $37 million, making it the highest-grossing restaurant in the United States.[102] The Sky Dive Restaurant, on the 44th floor of the North Tower, was also operated by Windows on the World.[100]
In its last iteration, Windows on the World received mixed reviews. Ruth Reichl, a New York Times food critic, said in December 1996 that "nobody will ever go to Windows on the World just to eat, but even the fussiest food person can now be content dining at one of New York's favorite tourist destinations." She gave the restaurant two out of four stars, signifying a "very good" quality rather than "excellent" (three stars) or "extraordinary" (four stars).[103] In his 2009 book Appetite, William Grimes wrote that "At Windows, New York was the main course."[104] In 2014, Ryan Sutton of Eater.com compared the now-destroyed restaurant's cuisine to that of its replacement, One World Observatory. He stated, "Windows helped usher in a new era of captive audience dining in that the restaurant was a destination in itself, rather than a lazy byproduct of the vital institution it resided in."[105]

Other buildings

 
The World Financial Center andBattery Park City, next to the World Trade Center, were built on reclaimed land.
Five smaller buildings stood around the 16 acres (65,000 m2) block. One was the 22-floor hotel, which opened in 1981 as the Vista Hotel, and in 1995 became the Marriott World Trade Center (3 WTC) at the southwest corner of the site.[106] 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 northwest corner, housed the United States Customs Service and the U.S. Commodities Exchange5 World Trade Center was located at the northeast corner above the PATH station and 4 World Trade Center was at the southeast corner.[107] In 1987, construction was completed on a 47-floor office building, 7 World Trade Center, located to the north of the superblock.[108] Beneath the World Trade Center complex was an underground shopping mall, which in turn had connections to various mass transit facilities, including theNew York City Subway system and the Port Authority's PATH trains.[109][110]
One of the world's largest gold depositories was stored underneath the World Trade Center, owned by a group of commercial banks. The 1993 bombing detonated close to the vault.[111] Seven weeks after theSeptember 11 attacks, $230 million in precious metals was removed from basement vaults of 4 WTC, which included 3,800 100-Troy-ounce 24 carat gold bars and 30,000 1,000-ounce silver bars.[112]

Operating history

February 13, 1975, fire

On February 13, 1975, a three-alarm fire broke out on the 11th floor of the North Tower. Fire spread through the tower to the 9th and 14th floors by igniting the insulation of telephone cables in a utility shaft that ran vertically between floors. Areas at the furthest extent of the fire were extinguished almost immediately and the original fire was put out in a few hours. Most of the damage was concentrated on the 11th floor, fueled by cabinets filled with paper, alcohol-based fluid for office machines, and other office equipment. Fireproofingprotected the steel and there was no structural damage to the tower. In addition to damage caused by the fire on the 9th – 14th floors, water from the extinguishing of the fires damaged a few floors below. At that time, the World Trade Center had no fire sprinkler systems.[7]

February 26, 1993, bombing

Underground bombing aftermath
The first terrorist attack on the World Trade Center occurred on February 26, 1993, at 12:17 p.m. A Ryder truck filled with 1,500 pounds (680 kg) of explosives, planted byRamzi Yousef, detonated in the underground garage of the North Tower.[8] The blast opened a 100-foot (30 m) hole through five sublevels with the greatest damage occurring on levels B1 and B2 and significant structural damage on level B3.[113] Six people were killed and 1,042 others were injured during escape attempts complicated by smoke infiltration from the base of the building up to the 93rd floor of both towers. Many people inside the North Tower were forced to walk down darkened stairwells that contained no emergency lighting, some taking two hours or more to reach safety.[114][115]
Yousef fled to Pakistan after the bombing but was arrested in Islamabad in February 1995, and was extradited back to the United States to face trial.[116] Sheikh Omar Abdel Rahmanwas convicted in 1996 for involvement in the bombing and other plots.[117] Yousef and Eyad Ismoil were convicted in November 1997 for their carrying out the bombing.[118] Four others had been convicted in May 1994 for their involvement in the 1993 bombing.[119]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.[120]
Following the bombing, floors that were blown out needed to be repaired to restore the structural support they provided to columns.[121] The slurry wall was in peril following the bombing and loss of the floor slabs that provided lateral support against pressure from Hudson River water on the other side. The refrigeration plant on sublevel B5, which provided air conditioning to the entire World Trade Center complex, was heavily damaged.[122] After the bombing, the Port Authority installed photoluminescentmarkings in the stairwells.[123] The fire alarm system for the entire complex needed to be replaced because critical wiring and signaling in the original system was destroyed.[124] 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.[125] However, the memorial was destroyed following the September 11attacks. Names of the victims of the 1993 bombing are included in the National September 11 Memorial & Museum.[126]

January 14, 1998, robbery

In January 1998, Mafia member Ralph Guarino, who had gained maintenance access to the World Trade Center, arranged a three-man crew for a heist that netted over $2 million from a Brinks delivery to the eleventh floor of the World Trade Center.[9]

Other events

In 1981, an Aerolineas Argentinas airliner was guided away by air traffic controllers following radar signals that indicated it was on a collision course with the North Tower (1 WTC). The aircraft was flying at a much lower altitude than regulations recommended, while scheduled to land at nearby Kennedy International Airport.[127]
In 1983, on Memorial Day, high-rise firefighting and rescue advocate Dan Goodwinsuccessfully climbed the outside of the North Tower (1 WTC). His stunt was meant to call attention to the inability to rescue people potentially trapped in the upper floors of skyscrapers.[128][129]
The 1995 PCA world chess championshipwas played on the 107th floor of the South Tower.[130]

Proposed lease

In 1998, the Port Authority approved plans to privatize the World Trade Center.[131] 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 PropertiesCorporation and Boston Properties,[132] and a joint bid by Silverstein Properties and The Westfield Group.[10] By privatizing the World Trade Center, it would be added to the city's tax rolls[10] and provide funds for other Port Authority projects.[133] On February 15, 2001, the Port Authority announced that Vornado Realty Trust had won the lease for the World Trade Center, paying $3.25 billion for the 99-year lease.[134] Vornado 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.[135]Vornado later withdrew and Silverstein's bid for the lease to the World Trade Center was accepted on April 26, 2001,[136] and closed onJuly 24, 2001.[137]

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