To the west is a nearly level platform in front of the castle, and separated from it by a ditch wholly artificial, and in part filled up and covered by the stables. This ditch was formerly produced along the south front, and communicated with the Bow Burn ravine. A modern bank of earth conceals the town from the castle on this, the south-western quarter. The walls of Alnwick town were embattled, and probably built, under a licence to Henry Percy, in 1434, when he constructed the Bond Gate, now standing. It is uncertain whether the town wall was independent of the castle, as at Chepstow, or abutted against its outer wall, as at Carlisle. The main entrance to the castle and its principal postern were both outside the town. The former was approached from it by a town gate, the position of which is remembered, and its name preserved, in the way called “Narrow Gate.” The castle postern opens towards the river. The Lion gateway in the south wall, leading to the town and the railway station, is altogether a modern structure, but may represent a by-gate communicating with the town. In plan the castle is irregular and many-sided; the west and south sides terminate, the one in the Abbot’s Tower, and the other in the Eastern or Ravine Tower, and are 125 yards and 213 yards long; and the side towards the river, and contained between these two towers, is 226 yards. The area within the walls is nearly 3 acres; that included by the ditch is near 7 acres. There is no single keep-tower. The keep is in plan an irregular polygon, set round with clustered towers, and containing a central court. This is placed nearly in the middle of the general inclosure, with which it was connected at three points: one, on the south, by a bold and lofty gallery which has replaced an original curtain, and projects 35 yards from the keep to a gatehouse which divides the eastern and western wards, and is known as the Middle Gate. The other connexions on the north side were two curtain walls, of which one reached from the keep 33 yards to the Falconer’s Tower, now rebuilt and shifted, and had upon it the Armourer’s Tower, now destroyed; and the other was a curtain, now removed, which extended 20 yards from the keep to the Postern Tower.