WTC (Twin Towers II)

Five smaller buildings stood around the 16 acre (65,000 m sq) block. One was the 22-floor Vista Hotel, later a Marriott Hotel, that was squeezed between the two towers. Three low-rise buildings in the same hollow tube design as the towers also stood around the plaza; they housed the US Customs Service and the US Commodities Exchange. In 1987, a 46-floor office building called 7 WTC was built north of the block. Under the block was a highly profitable underground shopping mall, which in turn led to various mass transit facilities, particularly the New York City subway system and the Port Authority's own PATH trains connecting Manhattan to Jersey City.

The excavation of the foundations of the building, known as the Bathtub, located on the former Radio Row, 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 cubic meters) 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 m sq) of landfill in the Hudson river next to the World Trade Center site, which became the site of Battery Park City

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. One source estimates the 1993 value of the gold at one billion dollars, believed to be owned by Kuwaiti interests. That same source claims that when the World Trade Center was destroyed, the amount of gold "far exceeded the 1993 levels." The gold was finally recovered in its entirety in late 2001.