A U.S. flag flies at a makeshift altar (top) overlooking the investigation at the United Airlines Flight 93 crash site in Shanksville, Pennsylvania, on September 16, 2001.
Hijackers affiliated with the al Qaeda terrorist network had planned to divert the California-bound plane to Washington, D.C., as part of the September 11, 2001, attacks. Passengers, however, fought back, crashing the plane before it could meet its mark.
Today a flag-bedecked fence cordons off the field, pictured at bottom on June 20, 2006.