The Château de Châteaudun is a castle located in the town of Châteaudun in the French département of Eure-et-Loir. The castle was built between the 12th and 16th centuries. The Count of Blois Thibaut V had the keep built around 1170. The Sainte-Chapelle was built between 1451 and 1493. The choir and the high chapel were built between 1451 and 1454, with the nave and the oratory between 1460 and 1464. Jehan de Dunois, the bâtard d'Orléans (Bastard of Orléans), built the west wing (the "aile Dunois") between 1459 and 1468.