A part of the Koufonisia complex, Keros is a tiny, uninhabited, and harbourless island, southeast of Ano Koufonisia. It has been one of the most important islands where the Cycladic civilization was flourished. In ancient documents, it is referred to as Keria and during that time it was united with the small island Daskalio.
Underneath the water-canal that separates Keros and Daskalio nowadays has been found the main settlement of the time which sank because of earthquakes and other geological reasons. During Medieval times Keros was a base for pirates. After that, and until 1952, it belonged to the monastery of Hozoviotisa, when it became a property of the Greek government.
Keros is very significant in terms of understanding the Cycladic civilization. This is the place where many small Cycladic statues and items of everyday use were excavated. And while on Daskalio there is still a defensive settlement standing, Keros was probably a sanctuary that was receiving all the holy items that was taking part in sacrifices or other rituals.
Keros today is considered an archaeological site and is uninhibited. Currently, there are no any guided tours or visits to the island.