On September 11, 2001: Two hijacked airplanes crashed into the World Trade Center, while another targeted the Pentagon in Arlington, VA, and a fourth crashed down in a field in Pennsylvania. Nearly 3,000 people and an additional 400 first responders were killed in the coordinated attacks.
10 YEARS LATER
On September 11, 2011: A dedication ceremony was held at the National September 11 Memorial and Museum on the 10th anniversary of the attacks. The memorial opened to the public the next day.