château, royal or seignioral residence and stronghold of medieval France—the counterpart of the English castle of the period. In such a fortress, peasants of the surrounding country took refuge during time of war. The early fortified château, called a château-fort, reached its culmination in the late 15th cent., when the magnificent feudal Pierrefonds was built near Compiègne. The 16th-century château, with its gardens and outbuildings, was usually surrounded by a moat, but was only lightly fortified. Notable châteaus of the transition period between the military château and the later country estate with extensive landed property are those of the Loire, Indre, and Cher valleys, such as Chambord, Amboise, Blois, Chenonceaux, Azay-le-Rideau, and Chaumont.

Château-Thierry, town (1990 pop. 15,830), Aisne dept., N France, on the Marne River. The town was the focal point of the second battle of the Marne (1918), which ended the last German offensive of World War I. An imposing monument to the U.S. soldiers who fought in the battle is just outside the town. The birthplace of Jean de La Fontaine is preserved as a museum.

Château-Renault, François Louis Rousselet, marquis de, 1637-1716, French vice admiral and marshal. He escorted the deposed king of England, James II, to Ireland (1689), fought against the Anglo-Dutch fleet at Beachy Head (1690), and commanded the Franco-Spanish fleet that was destroyed (1702) at Vigo.

Château d'If, castle built in 1524 on the small rocky isle of If, in the Mediterranean Sea off Marseilles, SE France. Long used as a state prison, it was made famous by Alexandre Dumas's Count of Monte Cristo.