The city is dominated by a monumental rock that rises up to 270 metres in height already known to the Phoenicians as “promontory of Hercules” on which the Temple of Diana stands, a megalithic building linked to the worship of the water, as indicated by the nearby cistern dating from the ninth century BC. The historic district is lying in the shadow of this bastion and clings around its beating heart which is undoubtedly the Duomo, a gigantic cathedral built by Roger II, the Norman.