In its present form it consists mainly of buildings undertaken in the 16th century by Louis XII and Francis I and in the 17th century by Gaston d'Orléans (1608-1660), brother of Louis XIII. The twin-aisled, arcaded Great Hall (or Salle des Etats-Généraux) built by Theobald VI (reigned 1205-1218) survives from the Gothic phase. The most impressive part of the château is the north-west wing (1515-1524), built against the medieval ramparts for Francis I. François Mansart was employed to rebuild the south-west wing (1635-1639).