There was a bridge across the river, connecting one section of the city with the other, and it is said that there was a subterranean passage under the river also, which was used as a private communication between two public edifices--palaces or citadels--which were situated near the extremities of the bridge. All these constructions were of the most grand and imposing character. In addition to the architectural magnificence of the buildings, the gates and walls were embellished with a great variety of sculptures: images of animals, of every form and in every attitude; and men, single and in groups, models of great sovereigns, and representations of hunting scenes, battle scenes, and great events in the Babylonian history. The most remarkable, however, of all the wonders of Babylon--though perhaps not built till after Cyrus's time--were what were called the hanging gardens. Although called the hanging gardens, they were not suspended in any manner, as the name might denote, but were supported upon arches and walls. The arches and walls sustained a succession of terraces, rising one above another, with broad flights of steps for ascending to them, and on these terraces the gardens were made. The upper terrace, or platform, was several hundred feet from the ground; so high, that it was necessary to build arches upon arches within, in order to attain the requisite elevation. The lateral thrust of these arches was sustained by a wall twenty-five feet in thickness, which surrounded the garden on all sides, and rose as high as the lowermost tier of arches, upon which would, of course, be concentrated the pressure and weight of all the pile. The whole structure thus formed a sort of artificial hill, square in form, and rising, in a succession of terraces, to a broad and level area upon the top. The extent of this grand square upon the summit was four hundred feet upon each side. The surface which served as the foundation for the gardens that adorned these successive terraces and the area above was formed in the following manner: Over the masonry of the arches there was laid a pavement of broad flat stones, sixteen feet long and four feet wide. Over these there was placed a stratum of reeds, laid in bitumen, and above them another flooring of bricks, cemented closely together, so as to be impervious to water. To make the security complete in this respect, the upper surface of this brick flooring was covered with sheets of lead, overlapping each other in such a manner as to convey all the water which might percolate through the mold away to the sides of the garden. The earth and mold were placed upon this surface, thus prepared, and the stratum was so deep as to allow large trees to take root and grow in it. There was an engine constructed in the middle of the upper terrace, by which water could be drawn up from the river, and distributed over every part of the vast pile.