The Smithsonian National Air and Space Museum's annex, located near Dulles International Airport, houses aircraft and spacecraft that wouldn't fit on the National Mall. The hangar is enormous — a football-field-scale space containing over 200 aircraft and dozens of space artefacts, all suspended or displayed at close range.
The Space Shuttle Discovery, the SR-71 Blackbird, a Concorde, the Enola Gay, and a Lockheed U-2 spy plane are among the centrepieces. There is also a full restoration hangar with a glass wall where visitors can watch aircraft being worked on. Admission is free; only parking charges ($15). It is easily combined with a visit to the Washington Dulles airport observation tower.