The old Roman walls may still be seen but not in their integrity .
约1078年由征服者威廉一世开始在罗马城墙内侧建造一座中央城楼「白塔」。
The central keep , or donjon , known as the White Tower because of its limestone , was begun c.1078 by William I the Conqueror inside the Roman city wall .
罗马城墙