The two other towers cap the northern angles of the ward, and flank the main gateway. They are of irregular form, semicircular to the field and angular within. In diameter they are about 40 feet, and about the same height. They are of two stages, which have been domed. The walls of these four towers are from 14 feet to 16 feet thick. They are of flint faced with brick. Between the gate-tower is the gateway, composed of a larger and smaller portal, the latter very narrow. The present work is modern, but no doubt in this double entry represents the earlier openings. The ditch, two detached piers standing in it, and with these any traces of the drawbridge, are concealed by the modern causeway. In the west curtain, near the south-west tower, a flight of steps beneath hanging arches of brick descends from the ward level in the direction of the foot of the wall. This is much encumbered with ruin, but seems to have been a postern, opening upon the ditch. All the works of this outer ward are of flint, rubble-faced with brick, which material forms the lines of the embrasures. The quoins are sometimes of ashlar, as are the extensive string-courses and bands, and the dressings of the openings. Traces of herring-bone work in its west curtain, outside, will be accounted for afterwards. As the original castle was confined to the inner ward, its ditch everywhere encircled it. When the outer ward was added, the intercepted portion of the ditch was partially filled up, but the new work was included in a new ditch, which was an accurate prolongation of the old one, of equal depth and breadth, and continued in the same direction. Accurate observation will, however, detect two slight shoulders in the counterscarp, showing where began the curve of the old ditch.