The architecture of the Achæmenid palaces includes the pier and the column as the supports of the structure. Among the ruins of Pasargadæ at present only three piers and one column, the height of which still exceeds 36 feet, are standing. But at Persepolis and at Susa, the Persepolitan capital, with all its elegance and [Illustration: Fig. 124.--Plan of the _Apadâna_ of Artaxerxes (after Dieulafoy).] originality, has been studied in all its varieties. It is found in every part, but notably in the great state saloon or _apadâna_ of the palaces. It is thirteen times as high as its diameter at the base: its slender form reveals the imitation in stone of an original structure supported by light trunks of trees. The apadâna of the palace of Xerxes at Persepolis, situated on the middle platform, covered an area of nearly an acre and a quarter, and its roof was sustained by a hundred columns. Before the anterior façade rose a portico guarded by two gigantic bulls with human heads, partly built into the structure like those in the Assyrian edifices. The apadâna of the palace of Artaxerxes at Susa (fig. 124) was of no less gigantic proportions, and had a double portico on three of its sides; it covers an area of an acre and a half. The columns are not less than 18 feet 4 inches in diameter; slightly conical in shape, they are composed of long cylindrical drums, placed end to end, the base and capital being separated from the shaft. Two varieties may be distinguished.[56] The simplest type is to be seen in the interior halls of the palace of Xerxes at Persepolis. The base is formed of two tori placed one above the other on a square pedestal; the shaft is decorated all round with forty-eight flutings; the capital includes a series of ornaments borrowed from the architecture of Egypt; it is [Illustration: Fig. 125.--Susian capital restored (Louvre).]