One other building within the palace deserves mention, as it has been suggested that it may represent the remains of the famous Hanging Gardens of Babylon.[85] It is reached from the north-east corner of the Central Court[86] along a broad passage-way,[87] from which a branch passage turns off at right angles; and on the left side of this narrower passage are its two entrances.[88] It must be confessed that at first sight the ground-plan of this building does not suggest a garden of any sort, least of all one that became famous as a wonder of the ancient world. It will be seen that the central part, or core, of the building is surrounded by a strong wall and within are fourteen narrow cells or chambers, seven on each side of a central gangway.[89] The cells were roofed in with semicircular arches, forming a barrel vault over each; and the whole is encircled by a narrow corridor, flanked on the north and east sides by the outer palace-wall. This part of the building, both the vaulted chambers and the surrounding corridor, lies completely below the level of the rest of the palace. The small chambers, some of them long and narrow like the vaults, which enclose the central core upon the west and south, are on the palace level; and the subterranean portion is reached by a stairway in one of the rooms on the south side.[90] There are two main reasons which suggested the identification of this building with the Hanging Gardens. The first is that hewn stone was used in its construction, which is attested by the numerous broken fragments discovered among its ruins. With the exception of the Sacred Road and the bridge over the Euphrates, there is only one other place on the whole site of Babylon where hewn stone is used in bulk for building purposes, and that is the northern wall of the Ḳaṣr. Now, in all the literature referring to Babylon, stone is only recorded to have been used for buildings in two places, and those are the north wall of the Citadel and in the Hanging Gardens, a lower layer in the latter's roofing, below the layer of earth, being described as made of stone. These facts certainly point to the identification of the Vaulted Building with the Hanging Gardens.[91] Moreover, Berossus definitely places them within the buildings by which Nebuchadnezzar enlarged his father's palace; but this reference would apply equally to the later Central Citadel constructed by Nebuchadnezzar immediately to the north of his main palace. The size of the building is also far greater in Strabo and Diodorus than that of the Vaulted Building, the side of the quadrangle, according to these writers, measuring about four times the latter's length. But discrepancy in figures of this sort, as we have already seen in the case of the outer walls of the city, is easily explicable and need not be reckoned as a serious objection.[92]