In Assyria on the other hand, mortar seems to have been used more sparingly; when stone was employed as a building material, generally speaking no cement of any kind was used, the stones being carefully dressed so as to permit of no interstices, as for example was found to be the case with the stone retaining-wall round the ziggurat at Nimrûd; when ordinary crude bricks were employed, they were laid in a sufficient state of moisture to render them adhesive; while when burnt brick was the material in question, the mortar adopted was a mixture of clay and water. Bitumen however was by no means unknown in Assyria, but it was used chiefly under pavements or the limestone floors of sewers, to prevent leakage or infiltration. STONE The use of stone in Babylonia, as a building accessory, although seldom as a fundamental material, dates from the most ancient Sumerian times. A very early example of the use of stone for definitely architectural purposes in Babylonia is afforded by the pavement upon which a building at Lagash, found under the structure of Ur-Ninâ, was erected. The pavement[53] consists of slabs of limestone, three or four feet long, one and a half to two feet broad, and about six inches thick. The door-sockets, again, of some of the earliest rulers of Lagash have been brought to light, among which may be mentioned those of the illustrious Eannatum and Entemena, all being made of marble or some other hard stone, while in Eridu, one of the most ancient sites of civilization in the Euphrates Valley, stone seems to have been quite extensively used. The terraced artificial platform upon which the temple and city of Eridu were built was buttressed by a wall of sandstone, and the staircase which led up to the first stage of the ziggurat was made of polished marble slabs, which are now lying about casually on the mound; pieces of agate and alabaster were discovered, and granite was also employed there. Stone gate-sockets have been similarly found at Nippur and in the ruins of other early cities of Babylonia, while both the Semite Narâm-Sin, and the Sumerian Gudea a little later, brought heavy blocks of diorite from Magan, or Sinai, though apparently for sculptural rather than for architectural purposes. In the Neo-Babylonian era stone was employed to a greater extent: the procession pavement of the god Marduk at Babylon, discovered recently by the Germans, was formed of slabs of limestone, bearing an inscription of Nebuchadnezzar, while Herodotus tells us that the bridge which then united the two banks of the Euphrates was made of “very large stones,”[54] and according to the classical writers, Strabo and Diodorus, the famous hanging gardens of Babylon, which Koldewey would locate to the east of the palace, were supported by stone architraves. But the stone used only for exceptional purposes in Babylonia, was re-used time and again, the ruins being regarded as a quarry, and consequently the stone has for the most part disappeared entirely.