Paliokastro

On the western flank of Tilos, beneath the 654-metre peak of Profítis Ilías, lies Paliokastro, a fortified Byzantine settlement of the so-called Dark Centuries. Built during the Middle Byzantine period, when Arab raids threatened the Aegean, it likely served as a refuge for the island's rural population, Tilos then falling within the naval Thema of Samos. The enceinte, of solid quarry stone masonry with occasional brick courses, survives only in fragments, its original height and any wall walk now lost. Within the ring wall, later agricultural terracing has obscured the site's earlier phases, though the base of large stone substructures hints at a possible ancient predecessor. A long, rectangular cistern, once barrel-vaulted, and foundations in mortar masonry remain, alongside abundant pottery and brick fragments attesting to intensive occupation. The main entrance lay on the north-east, approached by a now-impassable route through collapsed terraces. The castle commands sweeping views across the Dodecanese, from Nísyros to Rhodes and the Anatolian coast, though no path now leads there; only a steady, unmarked climb over broken ground reaches its ruins.