The twin towers of the World Trade Center collapsed on September 11, 2001, as a result of al-Qaeda's September 11 attacks, in which terrorists affiliated with al-Qaeda hijacked four commercial passenger jet airliners, flying one into the North Tower (1 World Trade Center) and another into the South Tower (2 World Trade Center). The South Tower collapsed at 9:59 a.m., less than an hour after being hit by the hijacked airliner, and at 10:28 a.m. the North Tower collapsed. Later that day, 7 World Trade Center collapsed at 5:21 p.m. from fires that had started when the north tower collapsed. As a result of the attacks to the towers, 2,752 people died, including all 157 passengers and crew aboard the two airplanes. The collapse of the twin towers also caused extensive damage to the rest of the complex and nearby buildings. Debris from the collapsing towers severely damaged or destroyed more than a dozen other adjacent and nearby structures.

L'effondrement des tours du World Trade Center a été l'évènement central des attentats du 11 Septembre 2001, durant lesquelles chacune des tours jumelles a été frappées par un avion de ligne détourné. La tour sud (2 WTC) s'est effondrée à 9h59 (heure locale), moins d'une heure après avoir été frappée. La tour nord (1 WTC) l'a suivie à 10h28 (heure locale).