The whole of the walls of the Southern Citadel have been pillaged by brick robbers even below the pavement, the level to which our excavations usually extend (Fig. 54). Everywhere we have laid the walls bare as far as the bricks still remain in position. Here in the south-east corner we have gone still deeper and have dug down to the foundation fillings, reaching nearly to water-level. The fillings consist almost exclusively of sand and clayey earth, river settlement with occasional patches of ancient building material, rubbish, charcoal and ashes, bones and some broken pottery. Possibly the sediment was taken from the watercourse that flowed past the southern side of the Citadel, and which would then be considerably deepened and widened. The footings are carried down almost to water-level, of the same even thickness without any broadening. At this depth the soil is interspersed with the remains of a very ancient settlement, characterised, as in other quarters of the city, by pipe wells and much pottery. Thus in the foundations everything is avoided that could prevent the settlement of the walls, and they are perfectly free to sink vertically. In laying the foundations the doorways were left open. Hence there are separate blocks of buildings, which doubtless even before the floor-level was reached settled independently of each other during the course of erection. In order to bind these blocks together across the door spaces, beams of poplar wood soaked in tar were inserted at intervals and fixed in the wall head with short transverse pieces, thus forming huge ├──┤-rivets. [Illustration: FIG. 54.—Excavations in Southern Citadel, from the north. ]