In the centre of this spacious area, rose the <g>donjon</g> or Keep, circular in form, of enormous strength, crowning a lofty artificial mound, and commanding a wide and uninterrupted view of all the neighbouring approaches. The height of the mount, from the bottom of the fosse on the external side, was seventy feet; on the internal, sixty-nine; and with that of the walls and battlements, by which it was crowned, presented a commanding elevation on the east of ninety-six feet; and on the west, of one hundred and three. The walls, measuring from eight to ten feet in thickness, inclosed a nearly circular space, varying between fifty-nine and sixty-seven feet in diameter, which afforded accommodation for the garrison. The apartments, judging from the corbel stones still remaining, appear to have been arranged round the walls, converging towards the centre, from which they received their light, as from an open cupola. Externally there were neither loop-holes nor openings in the masonry, from which, as in other keeps, an army could be annoyed; so that it was only from the ramparts and battlements that the garrison could repel an assault.--See Dallaway’s Rape of Arundel and Horsted’s History. Such in all probability was the ‘Castrum de Harundel’ when the Conqueror placed it in the hands of Roger Montgomery, and such as it had been when erected by the wise policy of King Alfred. At this time the Keep appears to have comprised the whole strength of the place, the barbican or outer rampart excepted; so that to give it the strength and space of a Norman castle, by contributing those improvements which the circumstances of the time demanded, and of which its natural position was highly susceptible, engaged the first care of its Norman possessor. The external walls, accordingly, were faced with a new casing of Caen stone; the whole structure was supported at intervals by broad flat buttresses; and on the south-east side of the Keep an improved [Illustration] entrance was effected, where the Norman art is still visible. It is a wide semicircular <g>archway</g> cut through the solid wall, ornamented on the inner side with a plain torus moulding, and terminated on the outer by a smaller arch, richly carved with the chevron and other ornaments in common use during the latter part of the eleventh century.[23]