Louvre

Originally replaced a large medieval fortress

Establish in the 16th Century to house the private art collection of King Francis I

In 1793, during the French Revolution, the Louvre became a national art museum and the private royal collection opened to the public. 

The museum has a collection of over 1 million works of art, of which about 35 000 are on display, spread out over three wings of the former palace.

Famous works: everything, pretty much

After entering the museum through the Louvre Pyramid or via the Carrousel du Louvre, you have access to three large wings: Sully, Richelieu and Denon. 

Descriptions of each wing: http://www.aviewoncities.com/paris/louvre.htm