On September 11^th, 2001 (often referred to as 9/11), a series of coordinated suicide attacks on the United States were carried out by al-Qaeda, a terrorist organization. The hijackers intentionally crashed two airplanes into the Twin Towers of the World Trade Center in New York City. Both towers collapsed within two hours, destroying nearby buildings and damaging others. The hijackers crashed a third airliner into the Pentagon, just outside Washington, D.C. and a fourth plane crashed into a field in rural Pennsylvania after some of its passengers and flight crew attempted to retake control of the plane. There were no survivors from any of the flights. These attacks changed the world like no other previous to it.