still standing not far from where the Çankaya Presidential Residence stands today. To the west, the Roman city extended until the area of the Gençlik Park and Railway Station, while on the southern side of the hill, it may have extended downwards as far as the site presently occupied by Hacettepe University. It was thus a sizeable city by any standards and much larger than the Roman towns of Gaul or Britannia. Ancyra's importance rested on the fact that it was the junction point where the roads in northern Anatolia running north–south and east–west intersected, giving it major strategic importance for Rome's eastern frontier. The great imperial road running east passed through Ankara and a succession of emperors and their armies came this way. They were not the only ones to use the Roman highway network, which was equally convenient for invaders. In the second half of the 3rd century, Ancyra was invaded in rapid succession by the Goths coming from the west (who rode far into the heart of Cappadocia, taking slaves and pillaging) and later by the Arabs. For about a decade, the town was one of the western outposts of one of Palmyrean empress Zenobia in the Syrian Desert, who took advantage of a period of weakness and disorder in the Roman Empire to set up a short-lived state of her own. The town was reincorporated into the Roman Empire under Emperor Aurelian in 272. The tetrarchy, a system of multiple (up to four) emperors introduced by Diocletian (284–305), seems to have engaged in a substantial program of rebuilding and of road construction from Ancyra westwards to Germe and Dorylaeum (now Eskişehir). In its heyday, Roman Ancyra was a large market and trading center but it also functioned as a major administrative capital, where a high official ruled from the city's Praetorium, a large administrative palace or office. During the 3rd century, life in Ancyra, as in other Anatolian towns, seems to have become somewhat militarized in response to the invasions and instability of the town. Byzantine history The city is well known during the 4th century as a center of Christian activity (see also below), due to frequent imperial visits, and through the letters of the pagan scholar Libanius. Bishop Marcellus of Ancyra and Basil of Ancyra were active in the theological controversies of their day, and the city was the site of no fewer than