Makronissos is a small island between Kea and Lavrio, parallel to the southeastern shores of Attica. Administrative, it belongs to Kea.
Its current name is due to its shape, as the island is narrow and long. In ancient times it was named Helen because it is said that passed Beautiful Helen when she was going to Troy with Paris.
It has an extend of 18sq.m. and the length of its coastline 28km. The highest point in the island is 264m.
According to archaeological findings, the island was inhabited since archaic times. Makronissos wrote its own page in the history of later Greece, since after the end of World War Two and years after, it was a banishment land for many Greeks.
Today the island is uninhabited but can be visited. Boats from Lavrio tour around the island.