An open air settlement of the Mesolithic era (9.000 - 8.000 BC) was found at the place Maroulas of Kythnos. It is believed that it was used as a station for passers-by, as at this era people were using caves to dwell. During the excavations round constructions were brought to light. Among the finding there was a human skeleton and plenty of stone tools made of flint, quartz and “optiano”. The settlement is the only open air one found in Greece.