on each level. Lighting was provided by arrow-slits, and the upper room in each tower, which was the only one to have a fireplace, was probably used as a lodging area. A latrine was also provided. Only the north tower is known to have been completed; however, its vaulted basement was mostly destroyed around 1317 when the roof and floors of the tower collapsed into it. It is not clear whether the south and east towers were ever completed. An estimate written in 1317 reveals that the towers were thatched, lacking castellations and a proper lead roof, but it is not known whether the work itemised in the estimate was ever carried out. The interiors of the towers were substantially modified in 1940. The interior of the inner bailey is now a broad, grassy area dominated by the stump of the keep at its eastern edge, which survives only up to its first floor. Despite the massive nature of the ruins, they preserve little of the original design apart from its unique ground plan. It consisted of a rectangular block measuring about by internally with seven projecting towers, a design found in no other medieval castle. Nothing remains of the interior and the uniqueness of its design makes it difficult to reconstruct its internal layout. Surviving 14th-century documents record that it contained a kitchen and a chapel, and had an iron door at its main entrance which was approached up a wooden stair. Like most Norman keeps, the entrance was situated on the first floor; the ground floor lacks any openings and it appears to have been constructed as a solid mass of masonry filled with clay. The near-total destruction of everything above the first floor means that the keep's original height is unknown, but it may have stood to a height of about or so. The unusual design of the keep may have been influenced by Roman architecture. The keep underwent at least two redesigns in the first half of the 14th century, possibly prompted by damage inflicted in earlier sieges. One of the redesigns involved constructing an adjoining square tower which some have suggested could have been used to mount a catapult; large stone balls, used as catapult ammunition, can still be seen in the inner bailey today. The building was recorded to be dilapidated for much of the 14th century despite repeated repairs, and had fallen into