Thus, then, this wall was built; the city is divided into two parts; for it is cut in half by a river named Euphrates , a wide, deep, and swift river, flowing from Armenia and issuing into the Red Sea . The angles of the wall, then, on either side are built quite down to the river; here they turn, and from here a fence of baked bricks runs along each bank of the stream. The city itself is full of houses three and four stories high; and the ways that traverse it, those that run crosswise towards the river and the rest, are all straight. Further, at the end of each road there was a gate in the riverside fence, one gate for each alley; these gates also were of bronze, and these too opened on the river.