The Longos Vales's Monastery foundation is attributed to D. Afonso Henriques in the second half of the 12th century.
The only enduring element of the primitive medieval construction with its clearly Romanesque style is the main chapel, the remainder of the group was subjected to remodelling work when it passed into the hands of the Society of Jesus.
Nowadays, the monastery is private property, with the exception of the church which continues to be part of the parochial headquarters of the parish.
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.