11 september 2001. On this date, two aircraft crashed into the Twin Towers of the World Trade Center, located on the southern tip of Manhattan in New York, and another aircraft into the Pentagon, near Washington D.C. A fourth aircraft crashed near Shanksville, Pennsylvania. All four passenger planes were flying within their normal schedules. Two aircraft were owned by American Airlines and two by United Airlines. These terrorist attacks are considered the largest in history. Nearly three thousand people from 87 countries were killed in the attacks, with 24 more missing and presumed dead.