Up to the present we have found about 15 of the towers on the mud wall only. They are the so-called Cavalier towers, and project both at the front and the back, thus placed astride on the wall. They were, of course, higher than the walls, but we can get no clue from the ruins as to the height of walls or towers, as only the lower parts remain. The towers are 8.36 metres wide and are placed 44 metres apart. Thus on the entire front there were about 90, and on the whole circumference—provided the town formed a square—there must have been 360 towers. How many there were on the outer wall we do not know. Ctesias gives the number as 250. No gateway has yet been found, which is not surprising, considering the limited extent of the excavations. During the Parthian period these lines of fortification can have been no longer in a condition to afford protection. On the town side of the mud wall there are Parthian sarcophagi, inserted in holes dug in the wall itself. While the foundations of the brick wall are below the present water-level, the mud wall stands on an artificial embankment. As a general rule mud walls were not provided with deep foundations. The mortar employed for the mud wall was clay, and for the brick wall bitumen was used. The same method of construction can be recognised in other parts of the city, where it is better preserved and can be more satisfactorily studied. At the northern end of our line of wall, which encloses the mound of ruins, called “Babil,” with a hook-like curve, the inner wall also was built of brick. This appears, at least, from the two deep trenches left by plunderers which occur here, but it must be inferred pending excavation. The digging for the valuable bricks which occurred in recent times has left deep traces in the otherwise smooth surface of the ground which we do not find in the attempted demolitions of more ancient times.