Five-storeyed, square tower (measuring 10 x 10 m.), around 20 m. high. It is made of local schist and marble (used in the frames of the openings, the corners and on the last floor).
It is a typical example of the free-standing defense tower of the Hellenistic period, and one of the highest preserved ancient buildings. It originally served for the protection of the surrounding cultivation area, between the ancient cities of Koressia and Poieessa. Around 1600 A.D., when the monastery of Aghia Marina was founded, the tower was incorporated in the precinct, again having defensive function. In 1958 it collapsed during an earthquake and many of its blocks were used as building material for the reconstruction of the adjacent buildings.
The north side of the monument is preserved in very good condition but the rest has collapsed and the debris has filled the interior of the tower. The wall masonry is built in the irregular trapezoidal system, with very few blocks occupying the full width of the wall.