Zenobia stands beside the river Euphrates, which flows close to its walls on the eastern side. This river, surrounded by high mountains, has no space in which to extend itself, but its stream is confined among the neighbouring mountains and between its rugged banks. Whenever it is swollen by rain into a flood, it pours against the city wall and washes not merely against its foundations but as high as its very battlements. The courses of stone in the walls, drenched by this stream, became disarranged, and the whole construction was endangered; he, however, constructed a mole of enormous masses of hard rock, of the same length as the wall, and forced the flooded river to expend its rage in vain, setting the wall free from any fear of injury, however high the river might swell. Finding that the city wall upon the northern side had become ruinous from age, he razed it to the ground, together with its outwork, and rebuilt it, but not upon its former site, because the houses of the city were so crowded together at that point as to inconvenience the inhabitants; but he proceeded beyond the foundations of the wall, beyond the outwork and the ditch itself, and there built an admirable and singularly beautiful wall, thus greatly enlarging Zenobia in this quarter. There was, moreover, a certain hill which stood near the city towards the west, from which the barbarians, when they made their attacks, were able to shoot with impunity down upon the heads of the defenders, and even of those who were standing in the midst of the city; this hill the Emperor Justinian surrounded with a wall on both sides, and thus included it in the city of Zenobia, afterwards escarping its sides throughout, so that no enemy could ascend it. He also built another fort upon the top of the hill, and thus rendered it altogether inaccessible to those who wished to assault the city, for beyond the hill the ground sinks into a hollow valley, and therefore it cannot be closely approached by the enemy; above this hollow valley the mountains at once rise on the western side. The Emperor did not merely watch over the safety of the city, but also built churches in it, and barracks for the soldiers: he also constructed public baths and porticos. All this work was carried out under the superintendence of the architects Isidorus and Joannes, of whom Joannes was a Byzantine, and Isidorus a Milesian by birth, being the nephew of that Isidorus whom I mentioned before. Both of these were young men, but showed an energy beyond their years, and both displayed equal zeal in the works which they constructed for the Emperor.