The bricks were always made with a mold, and were commonly stamped on one face with an inscription.

They were, of course, ordinarily laid horizontally.
Sometimes, however, there was a departure from this practice.

Rows of bricks were placed vertically, separated from one another by single horizontal layers.

This arrangement seems to have been regarded as conducing to strength, since it occurs only where there is an evident intention of supporting a weak construction by the use of special architectural expedients.
[Illustration: PLATE XVII.] The Babylonian builders made use of three different kinds of cement.

The most indifferent was crude clay, or mud, which was mixed with chopped straw, to give it greater tenacity, and was applied in layers of extraordinary thickness.