Chalandriani is a prehistoric citadel dating back to the 3rd millennium BC. Located on the northeast side of the island, it is one of the most important archaeological sites of the Cyclades. Kastri is a prehistoric settlement from the later years of the Early 2nd Cycladic period, where the excavations brought to light a graveyard with about 600 tombs, as well as ruins of inestimable value, which indicate that ceramic, stone and metalwork had been developed in the area. Various vases, jewellery and household items were also found during the excavations in the region indicating that this was a highly developed settlement. For hiking lovers, the two archaeological sites of Chalandriani and Kastri are linked with a long rough path that is definitely worthwhile as it leads in the mists of time.