The oldest is probably that at Wurka, dating as far back as 2000 B.C., known as the Bowariyeh. There are the remains of two stories, the lower occupying about 200 square feet. It is probable that a third story or a cella was placed above these, but nothing positive can be said on the subject, owing to the extremely ruinous condition of the building. The temple of Birs Nimroud, probably identical with the tower of Babel, is in a more satisfactory condition, the upper story having been preserved by a process of vitrification. The lowest story occupies a square measuring 272 feet on the side, each of the upper ones, of which it is supposed there were originally six, being 42 feet less. For the materials used in its construction we have the scriptural authority: “Go to, let us make brick and burn them thoroughly. And they had brick for stone, and slime had they for mortar” (Gen. xi.); slime being probably bitumen. M. Place discovered the remains of a tower at Khorsabad, with a winding ramp, which he thinks was originally seven stories in height. The walls were strengthened with buttresses and decorated with sunken panels, and from traces of colour found upon them it has been supposed that each floor was painted in a different hue. The area covered by the base is about one hundred and fifty square feet, and the total height was probably one hundred and thirty-five feet. The ruins of Persepolis are the best preserved of the ancient Persian buildings, those at Susa and Passagardæ being in too bad a condition to offer much that is interesting. They are situated in the plain of Mardacht, upon a terrace partly formed of masonry, and partly cut in the rock of the adjoining range of hills. The wall is composed of huge blocks of stone fitted together without mortar, but with the finest of joints. The terrace is reached by a splendid double flight of steps, upward of twenty feet in width, and on a grade easy enough to permit of the passage of long processions without interruption. At the head of the stairs is a propylæum, or outer gate, flanked by colossal human-headed bulls. Beyond this, a second staircase, ornamented with a triple row of bass-reliefs, gives access to the Chehil Minar, or great hall of Xerxes. This building occupies a rectangle about three hundred and fifty feet long by three hundred in width. It consists chiefly of a central hall and three lateral porticos, the roofs of which were sustained by 72 columns, 36 in the hall and 12 in each of the porches.