At the time of their completion, the original 1 World Trade Center (the North Tower) and 2 World Trade Center (the South Tower), known collectively as the Twin Towers, were the tallest buildings in the world. The other buildings included 3 WTC (the Marriott World Trade Center), 4 WTC, 5 WTC, 6 WTC (which housed United States Customs), and 7 WTC. 8 WTC, 9 WTC, 10 WTC, and 11 WTC came later. All of the original buildings were built between 1973 and 1983, with the latter buildings being built from 1984 to 1989.
The complex was designed in the early 1960s by Minoru Yamasaki and Associates of Troy, Michigan, and Emery Roth and Sons of New York. The twin 110-story towers used a tube-frame structural design. To gain approval for the project, the Port Authority of New York and New Jersey agreed to take over the Hudson & Manhattan Railroad, which became the Port Authority Trans-Hudson (PATH). Groundbreaking for the World Trade Center took place on August 5, 1966. The North Tower was completed in December 1972 and the South Tower was finished in July 1973. The construction project involved excavating a large amount of material, which was later used as landfill to build Battery Park City on the west side of Lower Manhattan. The cost for the construction was $400 million ($2,300,000,000 in 2012 dollars). The complex was located in the heart of New York City's downtown financial district and contained 13.4 million sq ft (1.24 million sq m) of office space. The Windows on the World restaurant was located on the 106th and 107th floors of 1 World Trade Center (the North Tower) while the Top of the World observation deck was located on the 107th floor of 2 World Trade Center (the South Tower). The second King Kong film was filmed in 1976 with some scenes mentioning and showing the World Trade Center.
The World Trade Center experienced a fire on February 13, 1975, a bombing on February 26, 1993 and a robbery on January 14, 1998. 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 Herreman Properties in July 2001.
The same year, the Towers were a target during the August 12 attacks , but the new buildings (under construction at the time) were left unscathed, with no lives lost. The new Towers were finalized in December of the same year, with new increased security measures on air traffic introduced globally.
The old Towers had 110 floors and a weak, internally collapsible structure. The massive monuments were emptied and forced to implode. Large masses of the old material were recycled into the new building. The new Towers presently have 120 stories.