The changes in its course to which the Euphrates was thus liable, appear only to have taken place _to the west_ of its present bed. After the most careful examination of the country, I could find no traces whatever of its having at any time flowed much further than it now does to the east, although during unusual floods it occasionally spreads over the plain on that side. The great mounds still rising on the eastern bank prove this. Supposing, therefore, the river from different causes to have advanced and receded during many centuries, between the Hindiyah marshes and its present channel, it will easily be understood how the ruins, which may once have stood on the western bank, have gradually been washed away, and how the existing flat alluvial plain has taken their place. In this manner the complete disappearance of the principal part of the western division of the city may, I think, be accounted for. It is more difficult to explain the total absence of all traces of the external wall and ditch so fully and minutely described by Herodotus and other ancient writers, and, according to their concurrent accounts, of such enormous dimensions. If a vast line of fortifications, with its gates, and equidistant towers, all of stupendous height and thickness, did once exist, it is scarcely to be believed that no part whatever of it should now remain. Darius and other conquerors, it is true, are said to have pulled down and destroyed these defences; but it is surely impossible that any human labor could have obliterated their very traces. Even supposing that the ruins around Hillah do not represent the site of ancient Babylon, there are no remains elsewhere in Mesopotamia to correspond with those great ramparts. If there had been, they could not have escaped the researches of modern travellers. But Herodotus states that, in the midst of each division of the city, there was a circular space surrounded by a lofty wall: one contained the royal palace; the other, the temple of Belus. There can be little difficulty in admitting that the mounds within the earthen rampart on the eastern bank of the river might represent the first of these fortified inclosures, which we know to have been on that side of the Euphrates. It is not impossible, as Rich has suggested, that the Birs Nimroud--around which--as it will be seen--there are still the traces of a regular wall, may be the remains of the second; or that the gradual changes in the course of the river just described, may have completely destroyed all traces of it.