At the northernmost part of the island, near the beach Agios Georgios, they have found the traces of a settlement that dates back to the Early Cycladic ΙΙ Period. The spot with the great archaeological interest is located in a clearing 15m above the sea level, some hundreds of meters to the west of the beach. Those that at first sight resemble dry stones are actually the remains of residences and fortifications dating back to the 3rd millennium B.C. Some broken pieces of vessels of the Roman times have also been found here. The archaic settlement may be related to Minoan or Phoenician explorers. Considering, though, its geographical position it could well be an intermediate station from and to Milos, as in the Neolithic era it exported its valuable minerals, especially obsidian, to the whole eastern Mediterranean.
From Kastellos another path westwards leads to a small and isolated beach exposed to the north wind, Lygaria.