History of the Peloponnesian War

The wall of the Peloponnesians was built in the following fashion. It had two encircling lines, the inner looking towards Plataea, the outer to guard against attack from the direction of Athens, and the two circuits were distant about sixteen feet from one another.

This interval of sixteen feet had in building been divided up into rooms assigned to the guards; and the whole structure was continuous[*](ie. the two περίβολοι were joined together by a roof.), so as to appear to be a single thick wall furnished with battlements on both sides.

And at every tenth battlement there were high towers of the same width as the wall, extending both to the inner and outer faces of it, so that there was no passage left at the sides of the towers, but the guards had to go through the middle of them.

Now at night when the weather was rainy the guards left the battlements and kept watch from the towers, which were not far apart and were roofed overhead. Such, then, was the wall by which the Plataeans were beleaguered.