"Located on an escarpment of the Upper Tigres River Basin that is part of the so-called Fertile Crescent, the fortified city of Diyarbakir and the landscape around has been an important centre since the Hellenistic period, through the Roman, Sassanid, Byzantine, Islamic and Ottoman times to the present. The site encompasses the Amida Mound, known as İçkale (inner castle), the 5.8km-long city walls of Diyarbakir with their numerous towers, gates, buttresses, and 63 inscriptions from different periods, as well as Hevsel Gardens, a green link between the city and the Tigris that supplied the city with food and water."
Source: UNESCO World Heritage Tentative List
A multi-view of Diyarbakir showing the citadel in the top middle view. Thanks to Onder of Turkey.