This section is adapted from 1911 Encyclopedia, and is probably out of date and not NPOV. It is also a little confusing. Fix as needed.
Originally a large and prosperous Phrygian city on the Persian Royal Road, Ankara became the center of the Tectosages, one of the three Celtic tribes that settled permanently in Galatia about 232 BC. The Celtic occupation caused the city's status to be damaged, and the town shrank to a mere village inhabited chiefly by the old native population.
In 189 BC, the Roman Consul Gnaeus Manlius Vulso occupied Ankara, and made it his headquarters in his operations against the Galatians. In 63 BC Pompey placed it (together with the Tectosagan territory) under one chief, and it continued under native rule until it became the capital of the Emperial Roman province of Galatia in 25 BC under emperor Augustus Caesar
By this time the population included Greeks, Jews, Romans and Romanized Gauls, but the town was not yet Hellenized, though Greek was spoken. Strabo (c. AD 19) calls it not a city, but a fortress, implying that it had none of the institutions of a Graeco-Roman city.
Inscriptions and coins show that its civilization consisted of a layer of Roman ideas and customs superimposed on Celtic tribal characteristics, and that it is not until c. 150 that the true Hellenic spirit begins to appear. Christianity was introduced (from the north or northwest) perhaps as early as the 1st century, but there is no shred of evidence that the Ancyran Church (first mentioned 192) was founded by St. Paul or that he ever visited northern Galatia. The real greatness of the town dates from the time when Constantinople became the metropolis of the Roman world: then its geographical situation raised it to a position of importance which it retained throughout the middle ages.
Both Persians and Arabs attacked Ankara during its period as a city of the Byzantine Empire. Seljuk Turks conquered Ankara around 1073. Although crusader Raymond IV of Toulouse drove them out in 1101, the Byzantines lost control, and Seljuks and their rivals battled for possession of the city.
Orhan I, second bey of the Ottoman Empire captured the city in 1356. Turkic leader Timur Lenk besieged Ankara as part of his campaign in Anatolia, but in 1403 Ankara was again in control of the Ottomans, where it stayed until the end of World War I
At the close of World War I, Turkey was under control of the Ottoman sultan and was being invaded by Greek forces. The leader of the Turkish nationalists, Kemal Atatürk established the headquarters of his resistance movement in Ankara in 1919 (See Turkish War of Independence). Turkey was declared a republic in 1923 and Ankara replaced Istanbul (formerly Constantinople) as the capital of the new country.
See also: Synod of Ancyra