The isolated square tower of Oinoe (8 x 8m.) preserves its northwest corner to a height of 14 meters and 32 courses. The four lower courses are constructed of concrete limestone; the upper courses are of conglomerate. The different building materials and masonry styles indicate two building phases, the more recent of which is datable to the mid-4th century B.C. From joist-holes visible in the interior of the tower which held the floor-beams, it is estimated that there were four floors, with the top row of joist-holes supporting the roof. Floors 2, 3, and 4 had archers? slots, and there is evidence that the upper floor had two windows for small catapults. The entrance was probably on the north side.
The location of the tower, its size, and equipment suggest a military use. It must have controlled the main Athens-Thebes road that ran a little to the north and served as a beacon because of its visual contact with at least three other strategic positions. The tower controlled the northwest borders of Attica and formed part of the more general Athenian system of defense during the 4th century B.C.