Located between the two Koufonissi islands and Schinoussa, Keros was as prominent during the period of the early Cycladic civilization as Delos was during Classical antiquity.
Rich in white, finely grained marble, the island stood as an important center of Cycladic culture. The ancient city was built at a spot connecting the island with the neighboring islet of Daskalio, nowadays sunken in the sea.
Excavation work carried out on the island’s western side have brought to light finds of exceptional importance, including over 100 marble figurines, among them ancient harpist and flute players, kept at the National Archaeological Museum of Athens, as well as an impressively sized statuette, 1.40m in height, of the Grand Mother deity.
During classical times, the island was known as Keria and was a member of the Athenian Alliance.
In medieval times it served as a base for pirates, while, later on, it was owned by the monastery of Panagia Chozoviotissa of Amorgos.
Today, the island is used as pasture land for grazing and belongs to Koufonissi. The island may be accessed by chartered boat service from Ano Koufonissi.