The area is divided into four wards, of which the “outer” covers rather more than its southern half, and the “town ward” about the eastern half of the remainder. The other, or north-western quarter, is again subdivided pretty equally into a “middle” ward, and a northern or “inner” ward. The whole area and the several wards are protected, where necessary, by walls and ditches. The curtain along the cliff seems to have been a mere parapet, save where, as in the inner ward, it supported interior buildings. The walls generally vary up to 30 feet in height, and from 4 feet to 5 feet in thickness. The outer ditch of the place, also the town ditch, commenced in a deep ravine close north of the keep, and was carried along the north front, skirting what are called “the Flats”; thence along the east front, between the wall and the town, and thence round the south end, and so beneath a part of the west front, until it is lost in the steep ground near the bridge, having been altogether nearly 700 yards in length. From this ditch branched a second, which traversed the place east and west, from the town ditch to the river bank, and which, placed to the south of a cross-wall, was the defence of the three northern wards from the outer ward. Another ditch, commencing in the ravine below the keep, runs north and south, and joined the preceding ditch, and thus protected the inner and middle wards from the town ward. Finally, from this branched another and still shorter ditch, which ran east and west into the river bank, and formed the defence of the inner from the middle ward; so that each curtain had its separate ditch. All the ditches are shown in Grose’s plan, but the town ditch, though to be traced, has been filled up and built upon. The deepest and broadest of the whole, and it is a formidable excavation, is that proper to the inner ward, something of the elevation of which is due to the heaping up of the contents of the ditch. These ditches seem all to have been dry. They are traversed at their ends by the curtains, and in three places, where the north curtain closes the end of the inner-ward ditch, and where the other end ran out upon the river slope, and where the east curtain closes the great cross ditch, are arched openings in the curtain at the level of the bottom of the ditch. Grose also shows a fourth arch in the wall of the middle ward. These were either drains or posterns. They are so nearly buried that only the tops of some of them are seen. Grose calls them doors, and they may be so. They seem original.