We might say, then, that Herodotus probably made a mistake--that his memory failed him in this instance, or that he mistook his notes on the subject.

Or we may explain his error by supposing that he confounded a canal from the Euphrates, which seems to have anciently passed between the Babil mound and the Kasr (called Shebil by Nebuchadnezzar) with the main stream.

Or, finally, we may conceive that at the time of his visit the old palace lay in ruins, and that the palace of Nerig-lissar on the west bank of the stream was that of which he spoke.

It is at any rate remarkable, considering how his authority is quoted as fixing the site of the Belus tower to the west bank, that, in the only place where he gives us any intimation of the side of the river on which he would have placed the tower, it is the east and not the west bank to which his words point.

He makes those who saw the treachery of Zopyrus at the Belian and Kissian gates, which must have been to the east of the city, at once take refuge in the famous sanctuary, which he implies was in the vicinity.
On the whole, therefore, it seems best to regard the Babil mound as the ziggurat of the great temple of Bel (called by some "the tomb of Belus") which the Persians destroyed and which Alexander intended to restore.
With regard to the "hanging gardens," as they were an erection of less than half the size of the tower, it is not so necessary to suppose that distinct traces must remain of them.