Cool sights to see in NOVA
Udvar Hazy Air and Space Museum Annex off route 28 in Chantilly. Awesome exhibits including Space Shuttle, SR71 Blackbird...
Museum of the USMC near Quantico. One of the best interactive museums I've ever seen!
Mount Vernon (George Washington's home), incredible interactive movie experience. When the winter at Valley Forge is covered, it actually snows in the theater. Pretty cool stuff, you have to go and see.
Arlington National Cemetary - Tomb of the Unknown Soldiers - changing of the guard AWESOME! "Here rests in honored glory, an American soldier known but to God"