The Babylonian buildings of the epoch of Nebuchadnezzar and Nabonidus must have resembled the Ninevite palaces and temples in form and architectural arrangement; but up to the present time we can only speak of them by conjecture, or according to the inexact descriptions of Greek travellers, and we cannot regret too much that the enormous Babylonian tells, such as those called the Kasr or Palace, Tell Amran, Babil and Birs Nimroud have yielded hardly anything yet of their archæological treasures. We must, then, for the present, confine ourselves to the description of the ruins of Khorsabad, Nimroud, and Kouyunjik, in order to reconstruct the principal forms of Mesopotamian architecture at the most splendid period of the Ninevite empire. § I. PRINCIPLES OF CONSTRUCTION. The limestone which is furnished in abundance by the lowest spurs of the mountains of Kurdistan enabled the architects of Nineveh not to employ brick exclusively, and sometimes to erect walls of trimmed ashlar. They used limestone especially for the basements of the buildings, which were more particularly exposed to the action of damp, so fatal to crude brick; they also had recourse to it for the construction of the ramparts of the royal palaces. But even here, on account of the dearness of the materials, which it was necessary to seek at a distance and to spend much time in hewing, stone is only employed for the outer facing of the wall; the builders use it sparingly, and are as niggardly of it as they are prodigal of brick. Accordingly, the walls which enclose the terrace of Sargon’s palace at Khorsabad are only of stone on the surface; the interior, or rather the nucleus of the structure, is of brick. The blocks on their external and visible surface are of variable length, but are placed upon one another in very regular courses of equal height and with crossed joints. Headers penetrate like wedges into the mass of the terrace to ease the layers of brick and bind them to the stone structure. In the lower courses of the rampart of the palace at Khorsabad there are regularly hewn blocks from 8 ft. 2 in. to 9 ft. 10 in. square; the blocks diminish in volume in proportion to the nearness of the layers to the summit of the rampart, which was 59 ft. high, including the battlements, which formed a parapet all round the terrace. [Illustration: Fig. 37.--Masonry at Khorsabad (after Place).] [Illustration: Fig. 38.--Section of wall at Khorsabad (after Place).]