The Smithsonian Castle looks like it should housing exotic treasures. But it doesn't really--at least, not many and not any more. The Smithsonian now sprawls across 19 different facilities, but this is the original building.
Originally opened in 1923 to display the collections of Charles Lang Freer, the Freer Gallery has since been merged with the Arthur M. Sackler Gallery to form the National Museum of Asian Art for the United States of America.
The Reynolds Center, in the heart of downtown Washington DC, combines two museums in one: it houses both the Smithsonian American Art Museum and the National Portrait Gallery. It has paintings, sculptures, photos, and drawings ranging from classical oil paintings to folk art to modern art.
If there's a combination that can draw the museum crowds almost as much as spaceships and airplanes, it's dinosaurs and whopping huge diamonds. And having a life-size elephant just inside the main entrance doesn't hurt either.
There are only a handful of museums in the world that get more visitors than the Smithsonian's National Air and Space Museum on the National Mall. It's a wonderful showcase of all things to do with space exploration and flight.