 The Castle of Bouillon is first mentioned in 988 in a letter to Godfrey Ι the Captive from his brother Adalberon, Archbishop of Reims.It is believed that this castle, and the estate connected, was an original patrimony of the dynasty.Bouillon was one of the central points of the dynasty's power, and was in their possession until it was sold by Godfrey of Bouillon to cover expenses for the First Crusade.