Washington D.C. has the largest number of museums per capita of any city in the world. In addition to the national monuments and the Smithsonian museums and galleries, the capital also has a number of fabulous private museums. The fact that they are private establishments means that you do have to pay for entrance, but it's well worth it. The one exception to this rule is the National Gallery of Art, which is free even though it's not part of the Smithsonian Institution. Also, the International Spy Museum, which opened in 2003, has caused quite a stir in the city as one of the more offbeat educational experiences in the city.