Conisbrough Castle was founded by William de Warenne, the first Earl of Surrey, who had taken part in the Norman conquest of England in 1066 and was rewarded by his father-in-law, William the Conqueror, with extensive estates in Yorkshire, Norfolk and Sussex. As part of these, Lord de Warenne was given the manor of Conisbrough, which had previously been owned by the late Harold Godwinson. The manor took its name from the Anglo-Saxon name for the settlement, "Cyningesburh", meaning "the king's fortress", and formed a large estate comprising 28 townships, centred on an Anglo-Saxon fortified burh at Conisbrough itself.