The Louvre is more than a world-class art museum. The Louvre was originally a fortified castle on the Seine, and the foundations of this medieval fortress can be seen in the its underbelly. In 1358, Charles V abandoned the royal Conciergerie across the river in favor of the Louvre. It remained the royal residence until the 16th century, when child-king Louis XIV moved into the Palais-Royal directly behind it to escape his would-be assassins. Today, the Louvre is wall-to-wall masterpieces, from ancient Egypt to early 19th century modernism. The famous glass pyramids designed by I.M. Pei were installed in 1989, and the Palais Royal's gardens feature contemporary sculptures by Daniel Buren. The Louvre is open late on Friday evenings, and entry is free on the first Sunday of the month.