Two beams retrieved from Ground Zero in New York City are actual parts of the World Trade Center, set side by side to represent the North and South Towers as they stood before the terrorist attack on September 11, 2001, and left untouched in the same condition after the towers fell. At 13 1/2 feet tall, the beams represent a 1/100th scale of the towers. Around them is a pentagon-shaped bench representing the Pentagon in Washington, D.C., also attacked on September 11, 2001, oriented the same way as the Pentagon, with its northwest part purposely defaced to mark where American Airlines Flight 77 struck. Between the beams and the bench are actual limestone pieces from the damaged Pentagon, placed to represent debris from the World Trade Center towers and the Pentagon. Nearby signs give the times and locations of the attacks, the time of the United Airlines Flight 93 crash in Shanksville, Pennsylvania, and the times when the World Trade Center North and South Towers collapsed. The attacks killed more than 3,000 Americans and threatened the nation, and the salvaged beams stand in remembrance of those who perished at the World Trade Center, the Pentagon, and on American Airlines Flights 11 and 77 and United Airlines Flights 93 and 175.