From history and art to a 900 year-old royal castle, London has so much to offer. Windsor Castle is still a working palace and the place Queen Elizabeth calls home. Besides royalty, London is home to some of the best museums in the world. Every year, more than 5 million people visit the British Museum, the United Kingdom's largest. The Tate Britain, originally built in 1897, houses more than 600 years worth of art. (CHRIS HEPBURN—GETTY IMAGES)