The Steven F. Udvar-Hazy Center near Washington is a museum you can't afford to miss. The three level center has engines, helicopters, ultra-lights, flight simulators, and experimental flying machines including the space shuttle Discovery, the Lockheed SR-71 Blackbird, Boeing B-29 Superfortress Enola Gay and the F-22 and X-35 fighters. This place is awesome for everyone who loves everything related to air/space history. If bringing young children keep in mind you'll have to walk or stand for long periods of time. If you really want the freedom to enjoy the entire site at your own pace skip the tour. I will recommend to get to the museum early in the morning if planning to take pictures since it gets really crowded later in the day. The museum has no admittance fee but the parking will cost you $15. Carpooling is highly recommended!