Some of the buildings carry no inscriptions, perhaps because the death of a king left them incomplete, and it is therefore pos sible that these fill the gap of 465-358, between Xerxes and Artaxerxes III., the only other king whose works can be identified. His name appears on a palace, with reliefs distinguished merely by their crudity, as well as on a staircase, bearing excellent re liefs, which was added to the side of a palace begun by Darius and continued by Xerxes; in the latter instance the sculptures possibly antedate the inscription by several generations.
The palace at Susa, built by Darius and rebuilt by Artaxerxes II. (404-358) after a fire, contains friezes in glazed and coloured bricks of lions, monsters and archers, reaching in the human figures a fairly high standard, but lacking the freshness of the best work at Persepolis, which indeed at the time of Xerxes had no peer in the world, but was soon eclipsed by the over-naturalistic work of Greece and declined rapidly throughout the fourth cen tury. Incidentally the Elamites had used glazed bricks at Susa; in other respects Mesopotamian influence in Persian art was de rived from Assyrian rather than Babylonian sources, in spite of the fact that the Assyrian empire fell before the Medes, but the Babylonian empire before the Persians themselves. Whether or not the Median empire acted as an intermediary cannot yet be decided, and the states of Elam and Anshan may be suggested as an alternative; the Elamites are known, from an inscription of Assurbanipal, to have followed the Assyrian custom of placing guardian monsters at the gates, but in other relevant points the arts of these kingdoms remain obscure.
Further evidence of the decay of Achaemenian sculpture is obtained from the rock-cut tombs of the kings. Of those at Nakht-i-Rustam near Persepolis, one bears the inscription of Darius, while the remaining three are usually connected with the names of his immediate successors, while the three similar tombs in the cliff behind the platform of Persepolis doubtless belong to later members of the dynasty and their sculptures exhibit inferior qualities. In every case the central part of the sculpture, 6o ft. in width, represents the facade of a palace, and above (as though upon the roof) is set a dais, supported by figures of sub ject races, upon which the king worships the gods, whose presence is indicated by the symbol of Auramazda and the Moon. The interiors of the tombs are simple chambers with niches cut in the rock for the reception of bodies; but a skeleton has been found at Susa buried in a bronze tub and, from the Greek accounts of his tomb, the same practice seems to have been followed in the burial of Cyrus.
Apart from the royal remains, nothing is known of the build ings of the age; houses must all have been of mud brick and it is questionable whether any temples existed. The only private sculptures of the age are a couple of reliefs found near the capital of the satrap of northern Asia Minor. The Achaemenid art was essentially dynastic, not national, confined to the king and his courtiers. The same condition extends to the minor arts; the
gold and silver ornaments and vessels (such as comprise the British Museum's "Treasure of the Oxus"), the stone vases, the engraved gems, are all luxuries suited only to the houses of rich nobles. Here again, as in architecture and sculpture, Persian art reveals itself as a modification of Assyrian art, with elements drawn from Egypt and Asia Minor, and a varying meas ure of Greek influence in the style.
In some statuettes from the Oxus treasure the Greek influence is overwhelming, but these may be later than the destruction of the Achaemenid empire by Alexander, which brought with it the eclipse of Asiatic art. In Syria and north India, however, the Achaemenian palace was imitated during the Hellenistic age, while in Mesopotamia and Persia it was ignored in the fashion for Hellenism. Apparently under both Macedonian and Parthian rule, a Hellenistic style was adopted in Persian buildings, and in the Parthian rock-carvings of Behistun Hellenistic methods are ap plied to oriental subjects of royal glorification: no other sculp tures of the Parthian age have been discovered in Persia, except a couple of satyr-heads by a Greek sculptor, which may have belonged to one of the numerous Greek settlers. The art of the Parthian period has left more traces in Mesopotamia where lay the capital of the empire; in Persia itself there is obscurity.
The Sassanids restored Persia to its former predominance in western Asia, with the result that art flourished once more within the borders of their ancestral principality. The traditions of the Parthian empire were, however, retained under the new rulers and it is possible that among the great mass of "Sassanian" material are included a few objects which in reality should be described as Parthian; this claim has been advanced both for buildings and for some pieces of silver plate. Since the Sassanid monarchy was modelled on the Achaemenid, the main features of the Persepolitan palace were preserved—the great hall for pub lic levees, the hall for private audiences with small adjacent offices —but these features were united into one and the same building. Moreover the method of construction was radically different from that of the pre-classical period ; instead of mud-brick walls, carry ing flat mud roofs on wooden ceilings, walls of small-cut stones or burnt bricks bound with mortar, carried barrel-vaults over the offices or corridors, and domes over the halls. The barrel-vault had already been employed on a grand scale in the palace at Hatra, which dates from the first or second century A.D. The develop ment of the dome is still obscure but it seems to have proceeded in the east rather than in the west : the Pantheon in Rome has a hemispherical roof, constructed on the lines of a barrel-vault, over a building itself following the same curve, while the use of the dome over a square chamber was apparently a Sassanian invention.