If you are at all a fan of aviation or interested in space travel, this is a must do while in D.C. It's conveniently located long the long row of Smithsonian museums between the Washington Monument and the U.S. Capitol Building, on the right side if progressing from the Washington Monument. There are many fun and interesting exhibits, including a mock-up of Chuck Yeagher's Bell aircraft used to break the sound barrier for the first time, a real nose section of an ex-Northwest Airlines 747 cockpit that you can walk into and check out, and a rock from the moon that you can actually touch! The price of entry is right...free! So check it out!