The Smithsonian In One Day.
We lived in Washington, D.C. for 25 years, and never managed to see all the Smithsonian, even though we spent more than 300 days there. It takes a week just to scratch the surface. Seeing the Smithsonian in one day is a joke, but if that’s all your schedule allows, here is how to see the high points in one day. This is a circle tour, so you can start anywhere on the route and go either direction. There is no chance of finishing the tour in one day if you wander around the museums until you stumble across the sights. You must either locate the route on the floor map when you enter, or ask a guard for directions.
Starting at the Air and Space Museum, see the Spirit of St. Louis, the Apollo Space Capsule, and the Wright Brothers plane in the main hall. Then the space station and the diorama of a Moon walk, with a real spacesuit that walked on the Moon, complete with Moon dust on the knees. At the opposite end of the building is half the Enola Gay, the A-Bomb plane. On your way out the Mall exit, touch the Moon rock on display.
Cross the Mall to the East Wing, National Gallery of Art. Go up the stairs and turn right, noting the Calder Mobile above. Go down the stairs and through the tunnel connecting the National Gallery buildings, then up by stairs or elevator to the main floor to the main Impressionist galleries. The National Gallery has so many Impressionist paintings that there are usually 2-3 shows on display. Ask staff how to find Renoir’s "Girl With a Watering Can" to get to the four rooms with the best Renoir, van Gogh, and Monet.
Back to the Rotunda ("Winged Mercury" on the fountain is the best preserved ancient Greek work in the world) and out to the Mall. Turn right to the Natural History Museum to see Dinosaur Hall, the Hope Diamond, the Coral Reef, and the Blue Whale.
Back on the Mall, go right to the Museum of American History. Check when the Star Spangled Banner will be displayed. This is the real thing, that flew amid "bombs bursting in air" and after more than 200 years, it’s fragile and kept in the dark most of the time. Split up. Ladies go see the First Ladies Inaugural Gowns and the White House China. Men go see the Antique Cars and railroad engines. Set a time to rendezvous back at the entrance. Cross the Mall. If you have time, cut across to the Holocaust Museum. Otherwise, go to the Freer Gallery’s Peacock Room. Back on the Mall, go right to funny looking building (Arts & Industry) next to "The Castle" for a quick look at the 1876 Centennial Display.
Back on the Mall, go right and walk through the outdoor sculpture garden in front of the Hirshhorn.
Time left? Return to your favorite for more.