The new 2 World Trade Center, which is currently on hold, is planned to have a diagonally-pointed roof, with no observation deck, and no mechanical floors.

[12] 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.

[20] In 1981, the Port Authority announced a $45 million plan to install sprinklers throughout the World Trade Center, following a major fire that occurred at the North Tower in 1975.

[21] On February 26, 1993, a Ryder truck filled with 1,500 pounds (680 kg) of explosives (planted by Ramzi Yousef) detonated in the North Tower's underground garage.

[24][25] In February 2001, the Port Authority leased the entire World Trade Center complex to Vornado Realty Trust.

[26] However, Vornado insisted on last minute changes to the deal,[27] and the next-highest bidder, Silverstein Properties, signed a lease for the complex on July 24, 2001.

[29][30] Three buildings in the World Trade Center complex, including 2 WTC, collapsed due to fire-induced structural failure.

[31] The light construction and hollow nature of the structures allowed the jet fuel to penetrate far inside the towers, igniting many large fires simultaneously over a wide area of the impacted floors.

[35] The South Tower collapsed at 9:59 a.m. after burning for 56 minutes in the fire caused by the impact of United Airlines Flight 175 and the explosion of its fuel.

[37] The structures were inspired by the architectural ethic of Le Corbusier and was the seminal expression of Yamasaki's gothic modernist tendencies.

[42] The Twin Towers' facades were made of high-strength, load-bearing perimeter steel columns which acted as Vierendeel trusses.

[54] The framed-tube 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.

[55] In designing the World Trade Center, Leslie Robertson considered the scenario of the impact of a jet airliner crashing into the building.