Portsmouth was once a mighty shipyard, and home to the Royal Navy. This is the only museum in the UK that covers the history of that storied Navy. Among its treasures are the famed "Enigma Machine" from World War II, that helped officers break Nazi codes, a life mask of Admiral Nelson (cast in 1800) plus intriguing exhibits of ship models, figureheads, medals, uniforms, model ships, weapons, and other memorabilia. The campaign of Trafalgar is particularly well covered and for the little ones there's a highly interactive children's center that helps bring all this history to life.