Late classical Fortress on "Prophet Elias" hill

On the height of Prophet Elias, in the island’s interior, foundations of large and medium stones reveal the presence of a fort. From the surviving architectural remains it appears to have had a square plan, with the main gate clearly visible and a bastion. Its form and construction materials point to the Late Classical period, when the island — then called Alonnesos — belonged to the Macedonian Kingdom. It is likely the fort was erected in the context of Macedonian expansion to enhance oversight and the security of sea routes crossing the area between Agios Efstratios, Chalkidiki and Lemnos.