The space shuttle Discovery makes its final voyage April 17 as it rides piggyback on a modified Boeing 747 by the George Washington Monument in Washington, D.C. The shuttle circled the National Mall several times before landing at Dulles International Airport, where it made the rest of the journey to the Smithsonian National Air and Space Museum annex in Virginia by truck. (U.S. Air Force photo/Senior Airman Torey Griffith)