The Château de Meung-sur-Loire is the great surprise of the town. From the front it looks like a refined 18th-century country house, all symmetrical white limestone with tall windows; walk around to the back and you find a hulking medieval fortress, with a great square tower and round corner turrets. The two-faced building is the result of nearly a thousand years of additions: the bishops of Orléans, who owned the château from the 12th century until the Revolution, kept rebuilding it to suit each successive age.
The tour goes through both halves of the castle and includes the famous underground rooms — vaulted cellars, dungeons, and the oubliette, a pit where the bishops locked their enemies and forgot about them. Alexandre Dumas opens The Three Musketeers with d'Artagnan riding into Meung on a yellow horse and falling into a fight in the inn, and the château makes much of the connection. The whole visit takes about an hour and a half.