I have a large set of pictures from within or without the citadel, along with many views of the city taken from its walls.

The Wikipedia says: "The foundations of the citadel or castle were laid by the Galatians on a prominent lava outcrop (39.941°N 32.864°E), and the rest was completed by the Romans. The Byzantines and Seljuqs further made restorations and additions. The area around and inside the citadel, being the oldest part of Ankara, contains many fine examples of traditional architecture. There are also recreational areas to relax. Many restored traditional Turkish houses inside the citadel area have found new life as restaurants, serving local cuisine.

The citadel was depicted in various Turkish banknotes during 1927–1952 and 1983–1989."

The present aspect of the Ankara citadel is almost exclusively of Byzantine and Turkish origin. Both set of walls were built by the Byzantine, using building material taken from the ancient Roman city (cut stone blocks, pillars, even altars and statues). The inner citadel came first, in the 7th century, when Arab Islamic troops raided Asia Minor regularly. These inner walls have a length of about 1150 m. After the Abbasid Caliph Harun al-Rashid besieged the city in 797, the citadel was repared and strengthened, and a second outer wall was added. That happened around 825. The outer citadel was 1500 m long (the south part of it is missing now), had 42 towers about 15 m high and enclosed an area of approximately 500 x 450 m (22½ ha.), this is: the better part of the Byzantine city at that time.
Ancyra was captured by Seljuk Turks in 1073, retaken by Crusaders in 1101 (on behalf of the Byzantine emperor) and again by Seljuks in 1127. They renamed the city ‘Engüriye’, by Westerners rendered as ‘Angora’.
After the collapse of Seljuk power (1243), the city and his castle passed under the control of various Turkish beyliks (principalities governed by Beys), fell under direct Ilhanlı (Mongol) rule in 1304, saw the Ottoman sultan Yıldırım Beyazıt I been beaten and captured by Timurlenk (Tamerlan) under its walls in 1402, and finally became Ottoman in 1414. The successive owners repared the citadel when necessary; het last extensive repair occured in 1832, by the order of İbrahim Paşa (future Khedive of Egypt) during the war he successfully waged against the Ottoman Empire.

Correspondent: J.M.Criel, Antwerpen
Source: ‘Guides Bleus: Turquie’ – Edition 1986.