 The Roman parts of the wall and towers are constructed of regular rectangular limestone blocks with a band of red tile running through them.The later medieval additions can be identified by the use of much larger blocks of limestone that cut through the red tiles in places and by the cross shaped arrow slits on the Multangular Tower.To the north of the Multangular Tower there is a stretch of the medieval city wall with the remains of the original Roman wall running parallel to it on the city side.