ABSTRACT
T H E character of the city wall has already been described (Fig. 9): its chamfered plinth and levelling courses of tile have been noted as features not present in the wall of the fort, but constant elsewhere. Putting on one side for the moment questions of date, the building of the wall, whenever it happened, had the effect of uniting city and fort by incorporating them in what was virtually a single defensive ring. When it was decided to enclose the occupied area it was natural that the fort should be brought into the new arrangement. On the northern frontage the wall was carried from the east (the Tower) to the north-east corner of the fort, to create the change of alignment at Aldermanbury Postern the diagnostic value of which has already been noted (p. 26). On the west the wall was taken away from the south-west corner of the fort at something more than a right angle. This wall ran westwards for about 1,200 feet before turning southwards near Newgate to make towards the river. It formed, therefore, with the west wall of the fort, the Aldersgate re-entrant, which must now be recognised as the out come of a logical development on the site rather than as an accident or freak of planning, determined as it might have been by some feature in the topo graphy which is no longer apparent. The effect of these developments was to turn the outward-looking north
and west walls of the fort into part of the defences of the city. It is at this point that the ‘double’ wall first noted behind Bastion 14 (p. 18) becomes significant. The original wall of the fort was comparatively slight in build, as befitted the offensive character of first/second-century forts in Britain:
with a width of under 4 feet it compared unfavourably with the massive city wall, whose width at the base, as already noted, was anything up to about 9 feet. The purpose of the addition, the inner ‘half’ of the double wall (Fig. 1 o ; Plates 3-14 ), seems to have been to bring the fort wall up to the same
strength as the city wall; and it is significant that the thickening is confined to those parts of the fort’s defences which were incorporated in the defences of the city as a whole.1 More accurately, it should be said that the thickening
