In the beginning of the 12th century, Philip Augustus decided to raise a big fortress, a true strategical guardian for Ile-de-France's area. Surrounded by moats, it had 8 towers and a small castle at the entrance, protected by a portcullis. Dwelling houses lined the curtains. The keep is located on the northern part of the surrounding wall: it's a circular tower (it used to be 30 metres high), isolated from the rest of the fortress. People used to enter in by a drawbridge.
In 1385, Charles VI the Mad gave Dourdan to his uncle, Jean duke of Berry: do you know this generous sponsor? He ordered to the Limbourg brothers the famous illumination book Très Riches Heures du Duc de Berry! Dourdan was King's property until 1478...
During war of Religion, the castle was occupied by duke de Guise's Catholics troops. Dourdan was almost in ruin... and duke of Biron seized it in 1591, for king Henri IV. In the beginning of the 17th century, the castle fell to the Orléans family. One century later, an attic was raised in the courtyard: the keep and the small castle were partitioned off. Then abandoned during the Revolution, the castle was converted into a jail, then into a school. Dourdan city owned it in 1961 and restored it.