Walls ran half across the outer court, and, from the end of these, light wooden bridges formed a communication with the wall of the inner court, so that in the event of the outer wall being stormed or the gates being carried by assault, the defenders could retire to the inner defences. The ends of these bridges rested upon irons projecting from the wall, and so arranged that they could be instantly withdrawn when the last of the defenders had crossed over, when the bridges would at once fall into the court-yard below. The inner wall was twelve feet higher than the outer one, and, like it, was provided with a crenellated battlement four feet high; there were projecting turrets at each corner, and one in the middle of each side.