History of the Peloponnesian War

At intervals of every ten battlements were towers of considerable size, and the same breadth as the wall, reaching right across from its inner to its outer face, with no means of passing except through the middle.

Accordingly on stormy and wet nights the battlements were deserted, and guard kept from the towers, which were not far apart and roofed in above.Such being the structure of the wall by which the Plataeans were blockaded,