According to later inscription (presumably from 17th century), St. Giles Church was founded in 1082 by Władysław I Herman as thanks for birth of his son Bolesław III Wrymouth. Actually it was founded probably not later than in 1138 by Hemran's son, Bolesław III Wrymouth. The church was restored between 1924 and 1926 and thoroughly between 1936 and 1938 with raising of the tower by one storey. The restorations changed the architecture of the church.
References: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.