For this purpose several tiers of arches were necessary; and these appear to have been constructed in the manner of a Roman amphitheatre, one directly over another so that the outer wall formed from summit to base a single perpendicular line.

Of the height of the structure various accounts are given, while no writer reports the number of the tiers of arches.

Hence there are no sufficient data for a reconstruction of the edifice.
Of the walls and bridge of Babylon, and of the ordinary houses of the people, little more is known than has been already reported in the general description of the capital.

It does not appear that they possessed any very great architectural merit.

Some skill was shown in constructing the piers of the bridge, which presented an angle to the current and then a curved line, along which the water slid gently.
[PLATE XV., Fig.