The French Company of Ottoman Lighthouses built that one in 1834, when it was also operated for first time. The height of its cylindrical tower is 29 meters and its focal plane 68 meters. It was established on 25 January of 1834 to honor the first year of Othonas Basel, with royal expenses, and is a work of Bavarian architect, Johan Erlacher. It was added to Greek Lighthouses Network after Balkans Wars in 1912-3.
It is located in front of Syros port, on the small isolated island Didymi or Gaidouronissi. During the 2nd World War the lighthouse was partially destroyed. In 1948 was repaired and since then works emitting one white flash every 2 minutes. It is the oldest and highest lighthouse of the Greek Lighthouses Network.