In July 2001, just two months before the terrorist attacks of September 11, the Port Authority agreed to lease the twin towers to Larry Silverstein, a New York City developer. Silverstein agreed to pay the equivalent of $3.2 billion over the next 99 years. At the time, over 99 percent of the 10.4 million square feet controlled by the Port Authority was occupied.
The impact of the two planes that hit the World Trade Center towers on September 11, 2001, was more devastating than any of the building’s designers and engineers had ever imagined. The first plane ripped a hole in the north tower from the 94th to the 98th floors, causing massive structural damage and igniting some 3,000 of the 10,000 gallons of jet fuel the plane was carrying. The second plane hit the south tower at an even faster speed, striking the corner and gashing the building from the 84th to the 78th floors.
The heroic efforts of the city’s fire and police departments and other emergency services helped 25,000 people escape from the site before the unthinkable occurred. The damage done at each point of impact forced the physical weight of the towers to be redistributed, and the undamaged part below the hole had to support the floors above. At the same time, the fires raging in both buildings weakened the steel trusses holding up each floor. With damage to a greater number of floors lower down on the building, the south tower gave way first, crumbling to the ground at 9:59 a.m., only 56 minutes after being hit. The north tower collapsed less than a half hour later, at 10:28 a.m.
Debris from the falling towers ignited fires in the remaining buildings of the trade center complex, including 7 World Trade, which burned for most of the day before collapsing at 5:20 p.m. Overwhelmed by horror, shock and grief, New Yorkers and people around the world trained their eyes on “Ground Zero,” where the fall of a treasured icon of American industry and ingenuity had left a gaping hole in the sky.