On this day in history, September 11, 2001, the United States was devastated by terror attacks in New York City, Arlington, VA, and Shanksville, PA.
Two hijacked planes crashed into New York City's World Trade Center towers, and both buildings came tumbling down. The crash left the city covered in billowing smoke, and millions of tons of rubble at "Ground Zero" where the World Trade Center once stood.
The hijackers crashed a third airliner into the Pentagon in Arlington County, Virginia. Passengers and members of the flight crew on the fourth aircraft attempted to retake control of their plane from the hijackers, and the plane crashed into a field near the town of Shanksville in rural Somerset County, Pennsylvania.
About 3,000 people died in the attacks and many suffer from health-related illnesses. President Bush declared a worldwide war on terror and the hijackers were quickly linked to al-Qaeda - the Islamic militant group set up by Osama Bin Laden.