World Trade Center (September 11 attacks)

On September 11, 2001, a series of coordinated terrorist attacks were carried out by the extremist group al-Qaeda against the United States. Two hijacked passenger planes were crashed into the Twin Towers of the World Trade Center in New York City, causing the buildings to collapse. Another plane hit the Pentagon, and a fourth crashed in Pennsylvania after passengers intervened. Nearly 3,000 people died, making it one of the deadliest attacks in U.S. history. This event profoundly changed global security policies, led to the U.S. War on Terror, and reshaped international relations.