that they were separated at that time by the Euphrates, until the river returned to its former and present bed, probably before the close of the Seleucid period. The greater part of the Southern Citadel is occupied by the enormous palace on which Nebuchadnezzar lavished his energies during so many years of his reign. On ascending the throne of Babylon, he found the ancient fortress a very different place to the huge structure he bequeathed to his successors. He had lived there in his father's life-time, but Nabopolassar had been content with a comparatively modest dwelling. And when his son, flushed with his victory over the hosts of Egypt, returned to Babylon to take the hands of Bêl, he began to plan a palace that should be worthy of the empire he had secured. Of the old palace of Nabopolassar, in which at first he was obliged to dwell, very little now remains. What is left of it constitutes the earliest building of which traces now exist within the palace area. Nebuchadnezzar describes it, before his own building operations, as extending from the Euphrates eastward to the Sacred Road; and the old palace-enclosure undoubtedly occupied that site. Traces of the old fortification-wall have been found below the east front of the later palace, and the arched doorway which gave access to its open court, afterwards filled up and built over by Nebuchadnezzar, has been found in a perfect state of preservation.[62] [Illustration: III. The Throne Room in Nebuchadnezzar's palace at Babylon, showing the recess in the back wall where the throne once stood.] The old palace itself[63] did not reach beyond the western side of Nebuchadnezzar's great court.[64] The upper structure, as we learn from the East India House Inscription,[65] was of crude brick, which was demolished for the later building. But Nabopolassar, following a custom which had survived unchanged from the time of Hammurabi, had placed his crude-brick walls upon burnt-brick foundations. These his son made use of, simply strengthening them before erecting his own walls upon them. Thus this section of the new palace retained the old ground-plan to a great extent unchanged. The strength and size of its walls are remarkable and may in part be explained by the crude-brick upper structure of the earlier building, which necessarily demanded a broader base for its walls.