40 COMPARATIVE ARCHITECTURE. The excavations of the Palace of Sennacherib, Nineveh, B.C. 705-681, and the Palace of Ashur-nasir-pal, Nimroud. b.c. 885-860, have revealed a large amount of information concerning Assyrian Palaces, and many of the sculptures with which the walls were lined are now in the British Museum. The method of roofing is still much in dispute. Some authorities hold that the long and narrow rooms were roofed with beams of poplar or palm, resting upon the summits of the walls, and that the large halls would have a central portion open to the sky, with porticos around, similar to that of a Roman atrium. Other autho- rities hold that the arch, which was used largely in the drains and water channels of the great platforms and in the city gates (No. 12 f), also played an important part in the construction of the palaces themselves, specially in view of the thickness of the walls, which would indicate that the architect had to provide solid abutments for arched vaults which supported a heavy roof. From a bas-relief found by Layard, it would appear that domed roofs both spherical and elliptical were also employed. THE THIRD OR PERSIAN PERIOD, from the time of Cyrus to that of Alexander the Great, has important remains of palaces, tombs and temples, at Susa, Persepolis, and Passagardae. The Persians having no architecture of their own, proceeded to adapt that of the conquered Assyrians, as later the Romans assimilated that of the Greeks. In the neighbourhood of their new cities, Susa and Persepolis, good stone was to be found, and, as a consequence, many architectural features, which are wanting in the earlier periods, are still extant. Persepolis, one of the important capitals of Persia, has inte- resting remains of no less than eight different buildings. These were erected on a great platform, 1,500 feet long by 1,000 feet wide, of four different levels, partly cut out of the solid rock and partly built up. It was from 20 to 50 feet above the plain and was reached l3y a wide stairway on the western side. The most important buildings erected by Darius are his Palace and the Hall of the Hundred Columns, while his son Xerxes built the Propyla?a, the Hypostyle Hall and a famous palace. The Hall of the Hundred Columns, 225 feet square, was probably used as an audience and throne-hall. It was surrounded by a brick wall, 10 feet 8 inches thick, in which were forty-four stone doorways and windows. The bas-reliefs are on a magnificent scale, representing the king surrounded by the arms of subject states, receiving ambassadors, rows of warriors and other subjects. The columns, of which only one is still in situ, had capitals of curious vertical
