months and the Green Chambers, so called because of the colour of their Gwespyr stonework. The chambers have basements specially designed for the storage of meat and wine and the upper storeys originally contained exceptionally fine accommodation. At the southern end of the castle, the Postern Tower, originally three storeys high, links the castle to one end of the town walls. The adjacent Upper Gate and the Postern Gate formed a rear entrance to the castle, protected by another barbican, drawbridges and a steep passageway. A mantlet of defensive terraces and cross-walls stretches around the south and eastern sides of the castle and originally prevented the undermining of the mural towers and thinnest stretches of the curtain wall. This side of the castle was protected by the Treasure House Tower, which held the Treasure House; the Tower-next-Treasure House; the Bishop's Tower, containing a sally port and the octagonal Red Tower, named after the red sandstone used in its construction, which linked to the other end of the town wall circuit. Stables, a blacksmith's workshop and storehouses once ran along the inside of the south-western corner of the castle. Town walls The town walls stretch for around from the north edge of the castle to its southeastern tip and mostly remain intact. The walls were built in the 13th century and originally protected by four mural towers, positioned in a disorderly pattern; the two gatehouses and the defences along the eastern salient were added in the 14th century. Only the foundations of the Exchequer Gate on the western side of the walls remain but the gatehouse would originally have been protected by two circular towers, with a rectangular glacis base to prevent undermining. The walls between the Exchequer and Burgess Gate at the north-west corner of the circuit are intact. The Burgess Gate has two circular towers protecting a vaulted passage way, again with a distinctive glacis base. The gatehouse is built from white limestone and yellow sandstone, with the stonework forming a chequered design; this was a common decorative approach at the time and would have symbolised local civic pride. Although the top courses have been lost, the gatehouse might originally have stood up to tall. The section of the walls to the east of the Burgess Gate has been lost. The walled circuit recommences in the north-east corner of the town, where the walls survive up to high, further