The Louvre Museum! The Louvre was constructed as a fortress in the early 13th century, rebuilt in the 16th, and became a museum in 1793. When it opened as a museum it contained some 2500 paintings, sculptures, and other bric-a-brac. Today it has some 35,000 exhibits on display including Leonardo da Vinci's Mona Lisa, which was actually stolen in 1911 but later recovered hehe.
					"On August 21, 1911, Leonardo da Vinci's Mona Lisa, one of the most famous  paintings in the world, was stolen right off the wall of the Louvre (famous museum in Paris, France). It was such an inconceivable crime that the Mona Lisa wasn't even noticed missing until the following day." - hahaha!