Diyarbakir, known in ancient times as Amida, spreads across a basalt plateau close to the banks of the Dicle river. The black basalt triple walls which encircle the old town give the city a rather ominous appearance. These ramparts are 5.5 km in length, have 16 keeps and five gates, are decorated with inscriptions and bas-reliefs, and represent a superb example of medieval military architecture.
Batman is Turkey's most important oil-producing center, with oil wells pumping the precious fuel dotting the surrounding area. North of Batman, the Malabadi Bridge, built in 1147, spans the Batman River. Undisturbed by time, peaceful waters still reflect the widest single-arch bridge of its day. Two guard towers ensured the bridge's security.
At Hasankeyf are the ruins of the 12th-century capital of the Artuchildren. The bridge, which once spanned the Dicle and connected the two pans of the city with the ruined palace inside the citadel, evokes the ghosts of a vanished dynasty. The 15th-century Zeynel Bey Mausoleum, attractively decorated with turquoise tiles, reveals Persian influence.
Siirt was an especially eminent city at the time of the Abbasid Caliphate. Among the city's monuments, be sure to visit the 12th century Seljuk Ulu Mosque and the 13th century Asakir Carsi Mosque. At Aydinlar (Tillo), only 6 km from Siirt, the Ibrahim Hakki Mausoleum Complex and nearby private Ibrahim Hakki Astronomical Museum are worth a visit. Siirt produces fine and large pistachio nuts and is known as well for its excellent goat-hair blankets and kilims.