CHÂTEAUDUN, a town of north central France, capital of an arrondissement in the department of Eure-et-Loir, 28 m. S.S.W. of Chartres by rail. Pop. (1906) 5805. It stands on an eminence near the left bank of the Loire. The streets, which are straight and regular, radiate from a central square, a uniformity due to the reconstruction of the town after fires in 1723 and 1870. The château, the most remarkable building in the town, was built in great part by Jean, count of Dunois, and his descendants. Founded in the 10th century, and rebuilt in the 12th and 15th centuries, it consists of a principal wing with a fine staircase of the 16th century, and, at right angles, a smaller wing adjoined by a chapel. To the left of the courtyard thus formed rises a lofty keep of the 12th century. The fine apartments and huge kitchens of the château are in keeping with its imposing exterior. The church of La Madeleine dates from the 12th century; the buildings of the abbey to which it belonged are occupied by the subprefecture, the law court and the hospital. The medieval churches of St Valérien and St Jean and the ruined chapel of Notre-Dame du Champdé, of which the façade in the Renaissance style now forms the entrance to the cemetery, are other notable buildings. The public institutions include a tribunal of first instance and a communal college. Flour-milling, tanning and leather-dressing, and the manufacture of blankets, silver jewelry, nails and machinery are the prominent industries. Trade is in cattle, grain, wool and hemp. Châteaudun (Castrodunum), which dates from the Gallo-Roman period, was in the middle ages the capital of the countship of Dunois.