A polygonal stone wall around the inner ward (5 acres) was protected by a landward ditch and two tower gates. Nearly all stone buildings show the same unusual foundations. The first, inner stone wall and one building are marked in blue, in contrast to the additions in violet. The most vulnerable point was the landward approach and perhaps that is why small, round, open-backed towers were built there for trained archers.

• The stone wall of the second bailey cuts off a very small segment of the ditch at the southwestern gate (see reconstruction, therefore the ditch has to be older than the masonry).
• The whole eastern section of the stone wall above the slope was later repaired and in doing so the outer wall was joined with a half-tower (compare the site plan).
• The remaining half-towers are close to the ditch.
• The towers are comparable to the tower at the residence of Bishop Bernward of Hildesheim which dates back to 1001.

Other ditches enclosed the middle or great bailey (20 acres), which was strengthened by similar half-towers and an outer or third bailey (16 acres). The defenses of the last one consisted of an earth rampart at the head of the promontory. Stockades probably closed the precipitous flanks.