page_title: World Trade Center (1973–2001)
section_title: Construction
hierarchical_section_title: World Trade Center (1973–2001) / Design, construction, and criticism / Construction
caption_attribution_description: Reverse image of World Trade Center during construction - May 1970 - Looking west from Broadway &amp; Vesey Street (not Fulton Street, as it appears) - North Tower preceded South Tower in construction - tower of old AT&amp;T building at upper right is actually on Fulton on south side of St Paul’s churchyard (not north side)
context_page_description: The original World Trade Center was a large complex of seven buildings in the Financial District of Lower Manhattan, New York City, United States. It opened on April 4, 1973, and was 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; and 2 World Trade Center, at 1,362 feet —were the tallest buildings in the world. Other buildings in the complex included the Marriott World Trade Center, 4 WTC, 5 WTC, 6 WTC, and 7 WTC. The complex contained 13,400,000 square feet of office space.
  The core complex was built between 1966 and 1975, at a cost of $400 million. During its existence, the World Trade Center experienced several major incidents, including a fire on February 13, 1975, a bombing on February 26, 1993, and a bank robbery on January 14, 1998. In 1998, the Port Authority of New York and New Jersey decided to privatize it by leasing the buildings to a private company to manage. It awarded the lease to Silverstein Properties in July 2001.
context_section_description: In March 1965, the Port Authority began acquiring property at the World Trade Center site. Demolition work began on March 21, 1966, to clear thirteen square blocks of low rise buildings in Radio Row for its construction. Groundbreaking for the construction of the World Trade Center took place on August 5, 1966.
  The site of the World Trade Center was located on landfill with the bedrock located 65 feet (20 m) below. 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. The slurry method selected by the 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 bentonite and 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. The 1,200,000 cubic yards (920,000 m³) of excavated material were used (along with other fill and dredge material) to expand the Manhattan shoreline across West Street to form Battery Park City.
  In January 1967, the Port Authority awarded $74 million in contracts to various steel suppliers. Construction work began on the North Tower in August 1968, and construction on the South Tower was under way by January 1969. 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. The topping out ceremony of 1 WTC (North Tower) took place on December 23, 1970, while 2 WTC's ceremony (South Tower) occurred on July 19, 1971. Extensive use of prefabricated components helped to speed up the construction process, and the first tenants moved into the North Tower in December 15, 1970, while it was still under construction, while the South Tower began accepting tenants in January 1972. When the World Trade Center twin towers were completed, the total costs to the Port Authority had reached $900 million. The ribbon cutting ceremony took place on April 4, 1973.
  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 m²) superblock.
caption: World Trade Center under construction in May 1971
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