of the fort's interior, suggesting that they may have been the site of wooden barrack blocks. The buildings are conjectured to have been largely timber-framed wattle and daub structures which have left little trace. Inner bailey The Normans divided the interior of the old Roman fort into two fortified enclosures, referred to as the inner and outer baileys. The inner bailey of the castle was, in effect, a castle within a castle, consisting of a walled fortification with a tower at each corner, surrounded by a moat and with a keep of unusual design at its eastern extremity, adjoining the old Roman curtain wall. The present stone fortifications of the inner bailey date mainly from the 13th and 14th centuries. They replaced the original wood and earth fortifications of the Norman inner bailey, which occupied a much larger area of the Roman fort's interior. Traces of the Norman bailey's ditch and earthen rampart, which stretched right across the interior of the fort, can still be seen today. The inner bailey protected the castle's most important domestic buildings, while the outer bailey was used for buildings of lesser importance such as a granary for the manor of Pevensey. The inner bailey's moat—which is fed by a spring—was probably over wide when first dug. The moat protected a mid-13th-century curtain wall, which is still largely intact, that divides the inner and outer baileys. A wooden bridge around long linked the inner and outer baileys, though the cost of maintaining it prompted its replacement in 1405 with a stone causeway and drawbridge pit that can still be seen today. The principal entrance to the inner bailey was through the early-13th-century gatehouse at the end of the entrance bridge, which had two D-shaped towers flanking a vaulted entrance passage. The towers were built on three levels with arrow slits in each level and basements below, which have survived intact. One of the basements can be reached via a spiral staircase; the other can only be accessed through a hole in the tower's floor and may have been used as a prison cell or oubliette. The gatehouse towers were built with open backs, which were probably closed by a wooden wall. Three other towers still stand on the east, north and south sides of the inner bailey's curtain wall. Built in the mid-13th century, they each had three floors which were accessed through separate entrances