Many additions and restorations were carried out in connection with these buildings, and they can clearly be distinguished, especially in the enclosing wall itself. The east end of the northern front is very instructive in this respect. We can distinguish the original building and a strengthening wall, the kisu, in front of it. Here it is of crude brick, but on the west front, like the kisu of Emach, it is of burnt brick. On the original building three periods lie superposed, as also on the kisu. Of each of these building periods slightly projecting towers are placed on the walls close together, and differently distributed, which considerably aids us in distinguishing the periods, as the mud-brick courses are frequently placed immediately over each other (Fig. 115). Inside the lowest kisu, somewhat farther to the west, there is a vertical gutter of the kind we have already observed in the inner city walls. In this were inscribed bricks of Esarhaddon (Fig. 116), with the statement that he built the zikurrat of Etemenanki. The two upper portions of the kisu must therefore belong to a later period, and the lower part of the main building to an earlier period, than that of Esarhaddon. The other excavations have produced in addition 12 stamped bricks of Sardanapalus (Fig. 117) and 4 inscribed bricks of Nebuchadnezzar (Fig. 118), all of which refer to the building of Etemenanki. Even if these bricks were not intended for the peribolos, but for the tower itself, their occasional use for the former is in no way surprising. All that we have been able to excavate so far is connected with the original building, of which the later repairing and rebuilding carefully follow the ancient line of wall. We need not therefore lay too much stress on the various periods. [Illustration: FIG. 118.—Nebuchadnezzar’s Etemenanki inscription. ] The surrounding wall is for the greater part a double wall, in which uniform broad chambers are constructed by means of cross walls. The ornamental towers on the inner walls are always placed between two doors of these chambers, while on the outside, where the two ornamental grooves that used to decorate both the towers and the intermediate spaces still exist in places, both towers and spaces are of the same breadth. There are buildings at other points of the encircling walls always joined to the outer wall. Large as they are, they have none of the characteristics of temples. Two large buildings lay on the east side, each with a large court surrounded by deep chambers uniform in size. In the corner there is a dwelling grouped round a courtyard, and on the south side there are four similar ones, which, although smaller, are very large and dignified mansions. At the east of the northern part the usual small private houses form an independent line of street. [Illustration: