The Smithsonian Institution

The Hope Diamond? Check. Paintings by Claude Money and Pablo Picasso? Check. Dorothy's ruby slippers from 'The Wizard of Oz'? Check. Flags carried to the moon and back? Check. A massive collection of historical items from across the globe can be found in Washington, D.C. thanks to the Smithsonian Institution. Made up of 19 separate museums, it is the world's largest museum complex. Nearly all the museums and exhibits are free. The Air & Space, American History, and Natural History are the favorites among tourists so expect large crowds. Others such as the American Art, American Indian and National Portrait Gallery should not be missed. Metro: Smithsonian or L'Enfant Plaza (for the museums and galleries on or near the National Mall).