At Alnwick the whole inner ward is a shell keep built upon a natural knoll. The main buildings, being the lord’s lodgings, are built against and form part of the wall, and the centre is an open court. The gatehouse is Norman, and part of the foundations of the wall, but most of the superstructure has been rebuilt twice over, though upon the old lines. There is a well in the wall, probably original, but encased in late Norman masonry. Alnwick being a sort of Castle Dangerous, and always open to sudden attack, the lord habitually lived within the keep, which was far more commodious than usual. Tickhill keep was a decagon, of which the foundations remain, to the top of the plinth, with the base of a flat pilaster capping each angle. The entrance was by a small door, just within which was the well. The mound stands on the _enceinte_, and the curtain runs up it on each side. About a quarter of the girth is within the castle area, and the rest outside. Part of Pickering keep is standing; it is late and polygonal. Here the mound is central, and stands on the line of a curtain which divides the area into two parts. At Ewyas-Harold, Builth, and Berkhampstead are traces of the foundations of the keep. At Kilpeck part of the wall is standing, and the well was within it, and is probably older than the masonry. Farnham keep is part of an inhabited dwelling, and has not been examined. At Oswestry is a fragment of the masonry, and at Whittington are traces showing that the mound was revetted, and also, in Decorated times, strengthened by four or five large mural drum towers. The foundations of Tonbridge keep show it to have been a slightly oval polygon, 86 feet by 76 feet, with fifteen external pilasters at the angles, and walls 11 feet 6 inches thick. This is attributed to Bishop Odo, but the noble gatehouse and walls below are later. The mound covers an acre, and is on the _enceinte_. Arundel has a good plain Norman doorway from the castle court, and an entrance by a gallery in the curtain from the gatehouse. Here is a chapel on the first floor, at the junction of the curtain with the keep, and near it is the well-chamber. The well is outside, and probably older than the keep wall. In the wall is a turnpike stair leading to the ramparts, and near its foot a small subterranean chamber, but both are later than the keep, and insertions. At Oxford the mound contains a crypt, an addition; but here, as at Wallingford, Hinckley, Leicester and Caerleon, the walls are gone, as at Bedford, so celebrated for its siege by Henry III. The mound at Quatford, having been the seat of Earl Roger, was, of course, fortified, though whether by masonry is unknown. There is, however, a deep well, which must have been within the keep. A tunnel and later flight of steps have been cut, and descend through the skirts of the hill from the outer ward. This passage strikes the shaft a few feet above the water level.