The Avenisi tower is rectangular in plan (8.6 × 5.5 m), built of mixed courses of cobble and rubble stone of various sizes, narrowing slightly toward the top. Only two stories survive. The first story has a rectangular entrance on the east; the door was later walled up. At the story's northwest corner, in both walls, is a rectangular niche. In the middle of the north wall, a wide fireplace covered by a horseshoe arch was completely walled up, and a buttress of triangular plan was built against the outside of the wall along its full length.