The city crowns a bold rocky bluff overhanging the gorge of the Tigris, which flows some 300 feet beneath it in a broad and sandy bed. The river is here wide and deep, and its modern name--_Shat_, the Arrow--testifies the rapidity of its current; but a little below the city its course is checked by a bridge and a weir. In the severe winter of 1910-11 it was frozen over so hard at this point that the caravans of camels were able to cross it on the ice. The river covers the eastern face of the city; and the ground falls fairly steeply along the southern face also. But toward the remaining two faces the approaches are over level ground. We possess many cities in Europe which are still entirely encircled by Roman or mediæval ramparts. Such are Carcassonne, Aigues Mortes, Avila, Lugo, and Rothenburg; and we may add Constantinople, though in this case the circuit is incomplete. But, having seen all these examples, we feel bound to put it on record that the basalt walls of Diarbekr are distinctly the finest of all. The walls are some forty feet high and about five miles in circuit, and are strengthened at frequent intervals by eighty massive towers. Most of these are semicircular, but some are semioctagonal. They are spaced about three and a half diameters apart, and project boldly from the curtain walls between. The line traced by the walls is irregular, skirting the edges of the hollows; and at each salient angle is a huge circular bastion. The gateways are somewhat insignificant, being mere holes in the walls flanked by a tower on either side: and this is characteristic of most Roman fortifications, the gateways of Lugo (for instance) being very similar in design.[18] The curtain walls are from ten to fifteen feet thick; thinner along the river front, where the precipitous basalt cliffs rendered assault almost impracticable; and thicker along the other three sides. These sides are further protected by a moat cut in the solid rock, but neither so deep nor so wide as the giant moat at Urfa. Along the inner edge of this moat, some paces from the base of the ramparts, is a low breastwork of masonry as at Constantinople and Carcassonne. A loopholed and vaulted gallery is carried along the top of the ramparts, and above this were the battlements, so that the defenders had a double banquette.[19] The towers are vaulted internally, and have double banquettes also; and the garrison could reach their stations by a double staircase at every tower. The citadel is at the north east corner overhanging the gorge of the river, and in the midst of it is a huge mass of masonry, once the mount of the demolished keep.