Ashur, a small Sumerian city-state on the middle Euphrates, began to gain political prominence during the pre-Hammurabi period. During the latter half of the 2nd millennium BC, the frontiers of Assyria were extended to include the greater part of northern Mesopotamia, and, in the city of Ashur itself, excavations have revealed the fortifications and public buildings constructed or rebuilt by a long line of Assyrian kings. The character of these buildings suggests a logical development of Old Babylonian architecture.
The fuller manifestation of Assyrian art and architecture is not seen until the 9th century BC, when Ashurnasirpal II transferred his capital from Ashur to Nimrud (ancient Kalakh; biblical Calah). The rise of Assyria to imperial power during this century and those that followed gave increased vitality to Mesopotamian architecture. The vast palaces brought to light in the 19th century emphasize the new interest in secular building and reflect the ostentatious grandeur of the Assyrian kings. Like the temples of earlier days, they are usually artificially raised up on a platform level with the tops of the city walls, astride which they often stand. Their gates are flanked by colossal portal sculptures in stone, and their internal chambers are decorated with pictorial reliefs carved on upright stone slabs, or orthostats.
In addition to the 9th-century structure at Nimrud, palace platforms have been exposed at Khorsabad (ancient Dur Sharrukin), where Sargon II established a short-lived capital of his own in the late 8th century BC, and at Nineveh, which was rebuilt in the 7th century, first by Sargon's son Sennacherib and then by his grandson Esarhaddon. On the platforms at both Nineveh and Nimrud, palaces and temples were multiplied by successive kings.
Sargon's palace itself, like that of Zimrilim 1,000 years earlier, is planned, first, around a gigantic open courtyard accessible to the public and, second, around an inner court of honour. From the latter the great throne room is entered through triple doorways, around which, in common with the main outer entrance to the palace, are concentrated a fine array of portal sculptures. The throne room has an adjoining stairway leading to a flat roof and a suite of living apartments behind. Other state rooms, conventionally planned, open onto an open terrace facing the mountains beyond. All the principal internal chambers are decorated with reliefs, except for the throne room itself, where mural painting seems to have been preferred. The individual purpose and function of the innumerable administrative and domestic offices must remain largely conjectural.
The gardens of Assyria, Babylon, and Persia were of three kinds: large, enclosed game reserves such as the garden of Eden described by the Hebrews in the Old Testament; pleasure gardens, which were essentially places where shade and cool water could be privately enjoyed; and sacred enclosures rising in man-made terraces, planted with trees and shrubs, forming an artificial hill such as the Hanging Garden of Babylon