On my way from Mardin to Tatev I make a short stop in Hasankeyf.

Hasankeyf was built around 363 AD by the Romans as a border fortress to prevent the Persian Sassanids from crossing the Tigris.
In the course of the centuries the rule over the city changed several times between the Romans, Persians, Arabs, Artukids, Seljuks, Mongols and Kurds. 

In 1116 a large bridge was built by the Artukids. Apart from the pillars, the bridge was partly made of wood, which was removed as enemies approached. Only the pillars are left of the bridge today.

In 2006, the Turkish government decided to build a dam nearby that would completely flood Hasankeyf, which is why the project is highly controversial.