WESTERN ASIATIC ARCHITECTURE, 35 those in which some of the most interesting palaces were erected at Susa and PersepoHs. The country remained under the rule of the Persians until the time of Alexander the Great, b.c. 333, when it became a possession of the Greeks. The conquest of Egypt by Cambyses, b.c. 525, and the dazzling impression left by the marvellous buildings of Memphis and Thebes, caused the development of the use of the column amongst the Persians. In the seventh century a. d., the Arabs overran the country and settled there — Bagdad becoming a new capital of great magnificence. Towards the close of the tenth century, the Turks, a barbarous people pouring in from the east, settled in the country, which is at the present moment in a desolate state owing to Turkish misrule. 2. ARCHITECTURAL CHARACTER. The banks of the Tigris and Euphrates presented only alluvial plains, where wood suitable for building was rare. The country, however, possessed an abundance of clay, which, being com- pressed in flat square moulds and dried in the sun, was the material of which were formed the huge platforms upon which temples and palaces were built. These immense plat- forms were at first faced with sun-dried bricks, and sub- sequently with kiln-burnt bricks, or in the later Assyrian period with stone slabs from the mountains that separate Assyria from Media. It will be perceived how the salient characteristics of the architecture may be explained by the nature of the materials at hand, for the walls being of brick, each unit, in general, was a repetition of its neighbour, and rarely of special shape. The buildings thus constructed could only be decorated by attached ornament, similar in principle to the mats and hangings spread over floors or walls as a covering, for the Assyrians either cased their walls with alabaster or with a skin of glazed brickwork of many colors. The arch was applied to important openings (No. 12) and also to vaults. In some cases it was not a true arch, but one formed by corbelling or projecting horizontal courses. The true arch however was also practised, being probably accidentally hit upon through the use of small units ; for as the Chaldaeans were unable to support walls over openings upon beams of stone or timber, owing to the lack of these materials in suitable forms, they had to devise some other means for doing so. It is a general law, which study and comparison will confirm, that the arch was earliest discovered and most invariably employed by those builders who found them- selves condemned by the geological formation of their country to the employment of the smallest units. Arches, therefore, in the absence of piers, rested on thick and
