Bisceglie Castle was originally a tower built around 1060-1070 by Normans and enlarged in the 13th century by Swabian counts. The tower was made later higher by the Angevines. Originally the castle was a four-sided building with five towers; today there are three towers left. The North-East tower is adjacent to the 12th century St Giovanni in Castro Church, which was included in the castle as its chapel during the Angevin time. Today the castle hosts an ethnographic museum.
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.