The first Vasknarva order castle (Neuschloss) was founded in 1349 on the northeastern border of Old Livonia. 1427–1442 a new castle (Vastne-Narva) was built, which became the centre of the vogtei of the Livonian Order. The castle was wracked in the Livonian War. Until the Great Northern War it was a fort of great importance, commanding the mouth of the Narva River. It has been known in Russian chronicles either as Syrensk or Syrenets. According the folklore St. Olga of Pskov narrowly escaped drowning when crossing the Narva rapids at Syrenets. Nowadays only parts of 3 meters thin walls have survived, mainly on the northern side.
Reference: Wikipedia
Towering 52 meters above the sea, Bengtskär lighthouse is the tallest one in Scandinavia. The building started in in 1905 after the shipwreck of S/S Helsingfors and was completed in 1906. The lighthouse was designed by architect Florentin Granholm. On December a special petrol lantern, designed and built in Paris, was brought to Bengtskär and installed atop the tower.
German fleet bombarded Bengstkär in the First World War in 1914. Since the Gulf of Finland was heavily mined, it was not until 1919 that the surrounding seas were declared safe for shipping, that the light was lit again.
After the war the military value of Bengtskär increased as part of the defence system of independent Finland. In Second World War (1941) Soviet Union made a suprise attack to island. After a bloody battle, the small Finnish garrison emerged victorious. Intermittent repairs to the facility continued during the post-war period.