The Monastery of Santa María de Mezonzo is a Romanesque style former monastery. Although it probably dates back to the time of the Kingdom of the Suebi, the current monastery was founded as a double convent by Abbot Reterico. According to Antonio López Ferreiro, the monastery was donated to the Asturian-Galician king Alfonso III el Magno in 870. Justo Pérez de Urbel, after comparing the names of the confirmatory of several documents related to the monastery, thinks that the correct date is the one given by Hinojosa, that is, the year 930.
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.