An estimated 200,000 people lived in Ancyra in good times during the Roman Empire, a far greater number than was to be the case from after the fall of the Roman Empire until the early 20th century. The small Ankara River ran through the center of the Roman town. It has now been covered and diverted, but it formed the northern boundary of the old town during the Roman, Byzantine and Ottoman periods. Çankaya, the rim of the majestic hill to the south of the present city center, stood well outside the Roman city, but may have been a summer resort. In the 19th century, the remains of at least one Roman villa or large house were 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.