The gateway itself was not placed immediately in the mud wall, but between four wing-like additions of burnt brick, in each of which was a doorway. Thus the Ishtar Gate had three entrances, the central one with fourfold doors, and one to right and left, each with double doors. The foundations of the main building are so deep that, owing to the present high water-level, we could not get to the foot of them (Fig. 21). The gateway wings are not carried down so far, and the walls that stretch northward still less. It is conceivable that those parts of the wall where the foundations are specially deep do not sink so much in the course of time as those of shallower foundations, and settlement is unavoidable even with these, standing as they do upon earth and mud. Thus where the foundations are dissimilar there must be cleavages in the walls, which would seriously endanger the stability of the building. The Babylonians foresaw this and guarded against it. They devised the expansion joint, which we also make use of under similar circumstances. By this means walls that adjoin each other but which are on foundations of different depths are not built in one piece. A narrow vertical space is left from top to bottom of the wall, leaving the two parts standing independent of each other. In order to prevent any possibility of their leaning either backwards or forwards, in Babylon a vertical fillet was frequently built on to the less deeply rooted wall, which slid in a groove in the main wall (Fig. 22). The two blocks run in a guide, as an engineer would call it. In the case of small isolated foundations, the actual foundation of burnt brick rests in a substructure of crude brick shaped like a well, filled up with earth, in which it can shift about at the base without leaning over, which gives it play like the joints of a telescope. In this way the small postament near the eastern tower of our gate is constructed, and also the round one which stands to the westward of it on the open space in front of the gate (Fig. 23). On these postaments and on similar ones in the northern gateway court and in the intermediate court must “the mighty bronze colossi of bulls and the potent serpent figures” have stood which Nebuchadnezzar placed in the entries of the Ishtar Gate (_Steinplatten_ inscription, col. 6). [Illustration: FIG. 23.—View of the Ishtar Gate from the west. ] Where the southern door adjoined its western buttress there were some remarkable and rather considerable ancient cavities in the wall, for which I cannot discover any certain explanation. They were filled with earth, and had not been meddled with in modern times. Later than these, but also of ancient times, there is a well hewn out in the northern wing. A narrow staircase led down to it, and could only be reached by a passage 50 centimetres wide cut through the wall, which opened on to the space in front of the gate. The exit was hidden away in a corner, and almost entirely concealed.