The nation's first major Memorial to 9-11 was unveiled on September 11, 2008, at the Pentagon. The memorial consists of 184 cantilevered benches representing each one of the individuals who perished when American Airlines Flight 77 crashed into the side of the Pentagon.CNN: Nearly Complete Pentagon Memorial Tells Story of 9/11 (May 24, 2008)

On September 11, 2001, American Airlines Flight 77, with 59 passengers on board, was hijacked shortly after takeoff from Washington Dulles International Airport. The flight, bound for Los Angeles, was piloted by terrorist Hani Hanjour into the western side of the Pentagon. The explosion resulting from the crash killed 125 people inside the building.CNN: Nearly Complete Pentagon Memorial Tells Story of 9/11 (May 24, 2008)