The world's most famous museum was originally constructed as a fortress, served as the royal palace of France for two centuries and was finally opened to the public as a museum in 1793. The entrance to this 800 year-old treasure is a new 67-foot glass pyramid. The treasures span nearly the entire history of art. Works from 5000 BC to the 19th-century are divided into seven categories: Oriental and Islamic Antiquities; Egyptian Antiquities; Greek, Roman and Etruscan Antiquities; Painting; Sculpture; Decorative Arts; and Graphic Arts. Of course, the Louvre's most famous resident is Leonardo da Vinci's Mona Lisa. People come from all over the world to get a glimpse of her and the other treasures that are kept here. Be advised, the Louvre is always crowded. Come as early in the day as possible and be prepared for long queues. Recent renovations have added additional space, which has improved the situation somewhat. Long queues aside, you cannot visit Paris without spending some time in Louvre.