A Dallas commuter train races across the railroad trestle atop the triple underpass overlooking the spot where President John F. Kennedy was shot in 1963, as people gather to commemorate the 50th anniversary of the shooting in Dallas, November 21, 2013. The railroad trestle plays a major role in some conspiracy theories about the assassination, with supporters of the theories believing that one or more gunmen may have fired on the president from the area in addition to Lee Harvey Oswald. Dallas police initially said that suspicious people were seen on the train tracks and some police officers ran to the area after the shooting. [Photo/Agencies]