Introduction

Together, the Black Tower with the surviving wall to the west and the lower tower to the east with the wall running down to it are the most important and most spectacular part of the defences to survive. [1] The walls and towers were built along a high ridge or spur on Carrow Hill and the land drops dramatically away on both sides. On the south a steep bank, some 4 metres or more high, runs down into the outer ditch and to the north and east there are views out to the river 40 metres below. [32-01 Map]

The Black Tower is the largest of the intermediate towers. It has an overall diameter of 10 meters and stands to a height of over 11 metres on the inner side though where the land drops away into the outer ditch on the south side it is 13.5 metres high and that is without the upper part of its parapet.

Apart from the Cow Tower this is architecturally the most complex of the towers. The outer face of the wall has knapped and squared flint work finely set with little mortar (presumably the reason for the name of the tower) and the ground-floor entrance and the doorway from the tower onto the wall walk to the west have stone surrounds with the remains of hood mouldings. The tower had a lower chamber that was vaulted and the upper chamber, reached by a partly-projecting turret on the west side of the tower with a spiral brick stair, had a massive brick fireplace. The stair continued up to the roof level where, presumably, there was a parapet walk commanding amazing views out over the river and the approaches to the city from the south. The tower had two obvious main functions. First, it provided a lookout platform commanding extensive views to the south. Second, the tower with the lower tower, the wall running down to the gate at King Street and the lower wall and the Boom Tower, formed an formidable and imposing sight for those approaching the city. At a more practical level, the large upper chamber with its fireplace may have provided a space for mustering troops or the guards of the watch.

The wall running up to the tower is in two sections with a breach of just over 20 metres. The first section, furthest from the tower, is just over 27 metres long and on the inner side there are six complete arches supporting the wall walk. At the west end is part of the jamb for a seventh arch. The wall walk survives though much broken away on the inner edge but only part of the outer parapet survives. [32-02 Plan]

Six arches of the wall walk arcade have been lost where the central section of the wall was demolished in the 18th century although the east jamb of the east arch of the sixth survives at the beginning of the next section.

After the breach, running up to the tower, the surviving wall is just over 47 metres long with eleven complete arches standing. Again the outer parapet has been lost apart from where it abutted the Black Tower. Here there were steps up from the wall walk to reach the upper chamber of the tower with a high but narrow parapet protecting the steps on both sides. On the outer or south side, the medieval brickwork of the crenellations survives.

Each arch has a loop through the outer wall constructed in brick and all the arches are formed in brick. There are also putlog holes lined with brick and regularly spaced for two levels of scaffold in each pier.