Assyrian palaces are however in a better state of preservation than those of Babylonia, and afford more material for the study of Mesopotamian architecture. First and foremost of these must be mentioned that built by Sargon (722-705 B.C.) at Khorsabad (cf. Fig. 8). The palace in question was built upon an artificial mound, like most of the important edifices in Babylonia and Assyria, these mounds serving a more practical purpose in Southern Mesopotamia, as by their means the buildings themselves were thus elevated beyond the reach of the waters of the inundating Euphrates. The mounds, sometimes formed of a mass of crude brick, sometimes of sand, gravel and other material, were kept together and protected by a casement wall of either burnt brick or stone. The revetment-walls at Khorsabad, which were formed of blocks of stone weighing sometimes as much as twenty-three tons and measuring 6 × 6 × 9 feet, gradually become thinner towards the top. The inner face of this stone wall in immediate contact with the crude brick mass, was left rough, which added to the general coherency of the whole. The total height of the wall at Khorsabad was some 60 feet, the foundations measuring 9 feet, and the retaining wall 46 feet, a parapet of 5 feet making up the total of 60 feet. When the roof was flat, it seems to have generally been surmounted by a parapet the top of which was crenelated. Nearly all the buildings portrayed on Assyrian bas-reliefs exhibit this crenelation, which was apparently a peculiar characteristic of Mesopotamian architecture, and indeed so popular did this style of arrangement become in later times, that even the tops of altars and stelæ were sometimes crenelated (cf. Fig. 14, C). Crenelated buildings are however not found in Babylonia till the time of Gudea and the dynasty of Ur (_circ._ 2450 B.C.). The foundation-mound upon which the brick town-wall of Dûr-sharrukîn (Khorsabad) was built was similarly faced with stone, the mound itself consisting of stones and rubble, but inside the palace, stone was only used for lining the walls, for the flooring of the more important rooms, and for the shafts, capitals and bases of columns, and other architectural accessories, the main body of the edifice being built entirely of brick. The outer walls of buildings were as a rule fortified with “buttresses,” made of stronger and more durable material than the walls themselves, while apparently the only foundations were the artificial mounds upon which the buildings were constructed. Unfortunately but little is known as to the internal arrangements of the buildings, and we are in considerable doubt even regarding the manner in which the various rooms were roofed.