The original World Trade Center was a complex with seven buildings featuring landmark twin towers in Lower Manhattan, New York City, United States. The complex opened on April 4, 1973, and was destroyed in 2001 in the September 11 attacks. The site is being rebuilt with five new skyscrapers and a memorial to the casualties of the attacks. As of November 2011, only one skyscraper has been completed; the other four are expected to be completed before 2020. One World Trade Center will be the lead building for the new complex, reaching more than 100 stories at its completion. It became the tallest building in New York City on April 30, 2012, and is expected to be finished by 2013. A sixth tower is awaiting confirmation.

   On September 11, 2001, terrorists hijacked American Airlines Flight 11 and crashed it into the northern façade of the North Tower at 8:46:40 a.m., the aircraft striking between the 93rd and 99th floors. Seventeen minutes later, at 9:03:11 a.m., a second team of terrorists crashed the similarly hijacked United Airlines Flight 175 into the South Tower, striking it between the 77th and 85th floors.

   At 9:59 a.m., the South Tower collapsed after burning for approximately 56 minutes. The fire caused steel structural elements, already weakened from the plane impact, to fail. The North Tower collapsed at 10:28 a.m., after burning for approximately 102 minutes. At 5:20 p.m. on September 11, 2001, 7 World Trade Center started to collapse with the crumble of the east penthouse, and it collapsed completely at 5:21 p.m. owing to uncontrolled fires causing structural failure.

By Luiza Dalsin Lopes