The walls are mostly dated to the Byzantine period. The surviving sections of the ancient walls of Ambracia are on the east side, and consist of massive rectangular blocks with finely worked faces. Wherever they rest on smaller cruder blocks we may have traces of an even earlier ancient wall. The Byzantines used the ancient walls and restored any missing sections with their signature rough masonry. The Ottomans increased the height of the walls and added gun embrasures. If you look closely, you may even locate a concrete gun emplacement dated to the Second World War. The massive multangular bastion to the left of the main castle gate was constructed against the inner wall by the Venetians, who adorned it with a cordon.