An old bridge dominates the town of Hasankeyf 110km/68mi northeast of Mardin. It crosses the Tigris which narrows at this point. The town was established as Cephe (Kiphas) by the Romans as a border post against the Persians. Under Byzantium it became an important bishop's see. The town's prosperity ended when it fell to the Artukids and Ayyubids
and later a Mongol invasion. Four arches remain from the old bridge which was restored in the 12th century. On a rock overlooking the bridge lie the remains of the Artukid palace, which can be reached via a steep flight of steps through three gateways. The palace also 12th century was known as the "Castle of the Forgotten" as nobody dared to mention its real name for fear of death. The Parthian king Arshak was incarcerated by the Romans and was tied with silver chains to the stuffed corpse of his general Varsak until he died. Outside the town stands 15th century Zeynel Bey Türbesi a cylindrical building constructed out of natural and blue bricks in a herringbone pattern. As a dam is being built in the Tigris valley (Ilisu Baraji), in 1994 part of the town is set to disappear under water.