The neighboring Greek islands of Kea and Makronisos belong to the Cyclades archipelago in the Aegean Sea off the coast of Attica. Makronisos, although currently uninhabited, has a long and interesting history. Traces of the first settlements on the island are dated to the fourth millennium BC. Makronisos, formerly known as Helena, used to be the seat of pirates and then the place where prisoners and refugees were quarantined. Political and concentration camps were also established here. In 1916, a British passenger ship disaster occurred in the isthmus between Makronisos and Kea.