The imposing hisar is the most interesting part of Ankara to poke about in. This well-preserved quarter of thick walls and intriguing winding streets took its present shape in the 9th century AD, when the Byzantine emperor Michael II constructed the outer ramparts. The inner walls date from the 7th century.
After you've entered Parmak Kapısı, the main gate, and passed through a gate to your left, you'll see Alaettin Camii on the left. The citadel mosque dates from the 12th century, but has been extensively rebuilt. To your right a steep road leads to a flight of stairs that leads to the Şark Kulesi, with panoramic city views. Although it's much harder to find, a tower to the north, Ak Kale (White Fort), also offers fine views.
Some local families still live inside the citadel walls and the houses here often incorporate broken column drums, bits of marble statuary and inscribed lintels into their walls. For a long time the neighbourhood here was extremely run-down but the past few years have seen the area gentrified somewhat although once you duck off the main route there are still many narrow, ramshackle alleys to explore.