Herodotus described these walls: "And here I may not omit to tell the use to which the mould dug out of the great moat was turned, nor the manner wherein the wall was wrought. As fast as they dug the moat, the soil which they got from the cutting was made into bricks, and when a sufficient number were completed, they baked the bricks in kilns. Then they set to building and began with bricking the borders of the moat, after which they proceeded to construct the wall itself, using throughout for their cement hot bitumen, and interposed a layer of wattled reeds at every thirtieth course of the bricks." According to this writer the outer wall was 14 miles in circumference, 93 feet thick, and 370 feet in height, but it is supposed that he included the city of Borsippa, across the river, within the length of wall, and no doubt he computed the height to include the lofty towers built at intervals along the wall, to give sentinels a wide outlook over the country. These walls the Greeks included among the wonders of the world, and probably ancient warfare could not have destroyed them. The Hanging Gardens of this great city were also enumerated among the world's wonders. These are said to have been built by Nebuchadnezzar for his Median queen, who wearied of the dull, flat country of Babylonia, and pined for her mountain home. The lowest terrace arose some 500 feet square, and three other terraces, supported by arches and pillars, were constructed above it, each smaller than the one beneath. These four platforms or terraces were covered with soil drawn up in carts, and the earth was deep enough to grow large trees, as well as all kinds of plants and vines. A pump house was located on top, water being drawn from the river and forced all through the structure, while the pipes were carefully concealed. Broad stairways led up to the uppermost terraces where a residence was built for the favorite queen. Hanging gardens had been built in Nineveh by former kings, but none so splendid as these nor on so gigantic a scale. Seen from afar, overtowering the high walls of the city, their height accentuated by the vast expanse of level land, the effect was that of a low mountain, clothed in verdure and scenting the breeze with the blended fragrance of its beautiful flowers.