V. In the same manner, since the walls of Theodosiopolis,[40] the bulwark of the Roman Empire on the river Aborrhas, had become so decayed by age that the inhabitants derived no confidence from their strength, but rather terror, as they feared that before long they would fall down, the Emperor rebuilt them for the most part, so that they were able to check the invasions of the Persians into Mesopotamia. It is worth describing what he did at Constantina. The original wall of Constantina was so low that a ladder would easily reach the top, and in its construction was greatly exposed to attack, and seemed hardly to have been built in earnest; for the towers were of such a distance from one another, that if the assailants attacked the space between them, the garrison of the towers would be too far off to drive them back; moreover, the greater part of it was so ruinous from age that it seemed likely soon to fall. In addition to this, the city had an outwork which was more like a siege-work to enable the enemy to attack it; for it was not more than three feet in thickness, cemented with mud, the lower part of it built of rock fit for making mill-stones, but the upper part of what is called white-stone, which is not to be trusted and is very soft, so that the whole work might easily be captured. However, the Emperor Justinian rebuilt the decayed part of the walls, more especially on the west and north sides; between every two towers of the wall he placed the third, so that since his time all the towers for the defence of the wall stand close together. He also greatly raised the height of the wall and of all the towers, so as to render the place impregnable to an enemy. Moreover, he built covered approaches to the towers, each of which towers contained three stories of vaulted stone, so that each one of them was called and really was a castle in itself, for what the Greeks call ‘phrourion’ is called a ‘castle’ in the Latin tongue. Besides this, Constantina used formerly to be reduced to great straits for want of water; there are indeed wells of good water outside the walls at the distance of a mile, round which grows a large wood of very lofty trees; within the walls, however, since the streets are not built upon level but upon sloping ground, the city in ancient times was waterless, and its inhabitants suffered much from thirst and the difficulty of obtaining water; but the Emperor Justinian brought the water within the walls by means of an aqueduct, adorned the city with overflowing fountains, and may justly be termed its founder. These were the works of the Emperor Justinian in these cities.