The eastern defences were reached via the Outer Main Gatehouse, which featured circular towers resting on spurred, pyramidic bases, a design particular to South Wales castles. Originally the gatehouse would have been reached over a sequence of two drawbridges, linked by an intervening tower, since destroyed. To the north side of the gatehouse was the North Dam, protected by three substantial towers, and which may have supported the castle's stables. Despite subsidence damage, the dam still holds back the North Lake. The South Dam was a massive structure, long, ending in a huge buttressed wall. The remains of the castle mill – originally powered by water from the dam – survive. Four replica siege engines have been placed on display. The dam ended in Felton's Tower, a square fortification designed to protect the sluicegates regulating the water levels of the dam, and the South Gatehouse – also called Giffard's Tower – originally accessed via a drawbridge, which led into the town.