Thus the inscription refers expressly to the building of Nimitti-Bel alone, and it is important to discover from which of the two walls it came; that, however, cannot be ascertained at present. It is true that the cylinders lay close to the narrow outer wall, but the fact must be taken into consideration that at the foot of the broader wall there is a much larger bank of its own fallen rubbish than there is at the base of the narrow one, and that any object such as the cylinders which came from it would roll down the bank much nearer the narrow wall than that from which it fell. If the cylinder belonged to the thick wall, Nimitti-Bel must have been a double wall; if it belonged to the narrow wall, the thick one may be Imgur-Bel; certainty can only be obtained by further excavation, which must level the greater part of the thicker wall, in order to bring to light the records which are probably hidden somewhere inside it. Such levelling would so greatly disfigure the ruins that hitherto I have avoided entering on the work, but it must be done before the conclusion of the excavations. The difficulties connected with the mud walls on the Kasr are very similar, though with some slight differences. Here also the simplest solution would be to identify the thick wall with Imgur-Bel and the narrow one with Nimitti-Bel. Many difficulties, however, arise against doing so. The moat wall of Imgur-Bel lies to the west of the Southern Citadel, where these mud walls actually do not survive. According to the above-quoted cylinder, Nebuchadnezzar surrounded Babylon on all four sides with the wall Imgur-Bel, while the two mud walls enclosed an area which undoubtedly was open towards the west. Here also complete and decisive understanding of the problem must await further excavations. [Illustration: FIG. 96.—Nimitti-Bel foundation cylinder of Sardanapalus. ] At the site of the 14th tower from the north in the thick wall there is below a piece of wall the breadth of the tower, which consists of Nebuchadnezzar’s burnt bricks laid in asphalt. A small drain roofed with high-pitched slanting bricks pierces this block of brickwork and continues for 19 metres farther to the east. This block of brickwork, which is 4.2 metres broad and contains the channel, gives the impression of being a roadway, and therefore one would expect to find a gateway at this place in the city wall (Fig. 97). Both walls, however, are so ruined here that nothing of the kind can now be recognised. The brickwork of the drain is strengthened with small pilasters at the sides, which grip into the ground like teeth, and would clearly prevent any slipping of the walls which slope towards the east. The drain itself also continues westward. [Illustration: FIG. 97.—Drain through inner city wall. ]