Claim: Al-Qaeda executed the September 11 attacks.

The World Trade Center was a large complex of seven buildings in Lower Manhattan , New York City , United States . It featured landmark twin towers , which opened on April 4 , 1973 , and were destroyed as a result of the September 11 attacks . At the time of their completion , the `` Twin Towers '' -- the original 1 World Trade Center , at 1368 ft ; and 2 World Trade Center , at 1,362 ft -- were the tallest buildings in the world . The other buildings in the complex included the Marriott World Trade Center -LRB- 3 WTC -RRB- , 4 WTC , 5 WTC , 6 WTC , and 7 WTC . All these buildings were built between 1975 and 1985 , with a construction cost of $ 400 million -LRB- $ in 2014 dollars -RRB- . The complex was located in New York City 's Financial District and contained 13400000 sqft of office space .   The World Trade Center experienced a fire on , 1975 , a bombing on , 1993 , and a robbery on , 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 Silverstein Properties in .   On the morning of September 11 , 2001 , Al-Qaeda-affiliated hijackers flew two Boeing 767 jets into the North and South Towers within minutes of each other ; two hours later , both had collapsed . The attacks killed 2,606 people in and within the vicinity of the towers , as well as all 157 on board the two aircraft . Falling debris from the towers , combined with fires that the debris initiated in several surrounding buildings , led to the partial or complete collapse of all the other buildings in the complex and caused catastrophic damage to ten other large structures in the surrounding area . The cleanup and recovery process at the World Trade Center site took eight months , during which time what remained of the other World Trade Center buildings was demolished .   The World Trade Center complex was rebuilt over a span of more than a decade . The site is being rebuilt with six new skyscrapers , while a memorial to those killed in the attacks and a new rapid transit hub have both opened . One World Trade Center , the tallest building in the United States , is the lead building for the new complex , reaching more than 100 stories upon its completion in November 2014 .