Ten years have passed since the September 11 terrorist attacks and yet there are still several mysteries that remain around the events of that fateful day.
1. Did Pentagon surveillance tapes showing the impact of Flight 77 ever surface?
In 2006, three security camera videos were released in response to a December 2004 Freedom of Information Act lawsuit. However, some theorists still argue that the blurry images are inconclusive and that the FBI is withholding at least another 84 surveillance tapes.
Photo: U.S. Department of Defense handout photo dated September 14, 2001 shows an aerial view of the destruction caused when a hijacked American Airlines flight slammed into the Pentagon on September, 11, 2001 in Arlington, Virginia. (REUTERS/DoD/Tech. Sgt. Cedric H. Rudisill/Handout)