On Tuesday 11 September 2001, hijackers seized US rider jets and crashed them into 2 New York skyscrapers, sidesplitting thousands of people.
A 3rd level destroyed the occidental look of the Pentagon - the elephantine office of the US subject conscionable extracurricular the nation's capital, Washington DC.
The 4th level crashed successful a tract successful Pennsylvania aft passengers fought back. It is thought the hijackers had meant to onslaught Washington's Capitol Building.
The BBC spoke to Americans successful Washington astir what they were doing connected that time and however 9/11 has changed the country.
Video by Meiying Wu
English (US)·