The Roman Emperor Trajan, a spirited and energetic man, appears to have been irritated at the thought that the boundary of his empire was fixed by the river Danube.[76] He was anxious, therefore, to throw a bridge across it, in order that he might pass it without its offering any obstacle when he marched against the barbarians beyond it. How he built this bridge I shall take no pains to describe, but shall let that be told by Apollodorus of Damascus, the chief architect of the entire work. No advantage accrued from it to the Romans, and the bridge subsequently was destroyed by the stream of the Danube and by age. Trajan built two forts on either bank of the river, and called that on the further side Theodora and that on the Dacian bank Pontem, from the name of the bridge; for the Romans call a bridge _pons_ in Latin. Since after this the river became impassable for ships at this place, owing to the ruins and foundations of the bridge, they forced the river to adopt a new channel and perform a circuit in order to afford them a passage beyond it. Both these forts fell into ruins through age and the assaults of the barbarians; but the Emperor Justinian rebuilt the fort Pontem, on the right bank of the river, with new and powerful fortifications, and thus secured Illyria. As for that on the opposite bank, named Theodora, he thought it unnecessary to bestow any care upon it, since it was exposed to the attacks of the barbarians in that region; but he built all the new fortifications which stand on the bank below Pontem at this day, which are named Mareburgus, Susiana, Armata, Timena, Theodoropolis, Stiliburgus, and Halicaniburgus. There is a small city near this place, named Ad Aquas, some small part of whose fortifications, which had become unsafe, were restored by the Emperor. Beyond it he built Bergonovore, and Laccobergus, and the fort named Dorticum, which he made into the existing strong fortification. He altered the solitary tower named Judæus into what may be called, and really is, a most beautiful fort. He rebuilt Bergus Altus, which formerly was deserted and altogether uninhabited, and also enclosed with a wall another place named Gombes. He rebuilt the fortifications of Crispas, which had become ruinous from age, and built Longiniana and Ponteserium in an admirable manner. At Bononia and Novum he rebuilt the bastions which had become ruinous. He rebuilt all the ruinous parts of the city of Ratiaria; and in many other places he either enlarged small fortifications or reduced over-large ones to a convenient form, in order that neither their smallness nor their excessive size might expose them to the attacks of the enemy; as, for example, he turned Mocatiana from a single tower into the more complete fort which it is at this day, whilst at Almus he reduced the space enclosed by the walls, which formerly was very great, thus enabling it to defy the attacks of the enemy. In many places he altered a solitary tower, an