The citadel (acropolis) of Proerna crowns the double summit of the rocky knoll known as "Gynaikokastro" at the easternmost and highest part of the ancient part of the city. It extends over ca. 200,000m2 and its circuit is trapezontial in plan. The south flank is preserved up to the height of eight courses, but the north flank probably has not been built. The defensive wall, which is 1,50 - 2,00m. in width, displays two faces constructed in irregular ashlar or isodomic trapezodial, firmly - jointed masonry.