Rochester Castle was originally a post-Conquest earth and timber fortification, founded by William the Conqueror. Built within the walls of the Roman town of Durobreve, in 1086 the fortress is mentioned in the Domesday Book. In 1088-9, Gundulf, bishop of Rochester founded the stone enclosure castle, when replacing the timber defences with an irregular curtain wall. In 1127, William de Corbeil, archbishop of Canterbury added the square four storey keep, which is defended by a tall protruding forebuilding. In 1215, when garrisoned by rebel barons, the castle endured dramatic seven week siege by King John, when the stronghold was breached by mines which collapsed part of the curtain wall and the adjacent tower of the keep. King Henry III and King Edward III made repairs to the castle, which remained a viable fortress in the 15th century but by the 16th century it was in decay, after a domestic fire destroyed the interior of the keep. 2 miles north-east is Upnor Castle.