Brindisi di Montagna Castle was built around 1200 and is situated on a large rocky ridge. The architecture is characterized by three main elements: The central part (a long the rocky ridge of the hill).The northern part, with the turret for lookout (later transformed by the Antinori family into the chapel of San Michele) and the southern part where there are few but significant wall traces embedded in the rocky elements.
Its defensive function is evident both from the presence of arrow slits and its position overlooking the intersection of the two routes leading to the fortress. It differs from the Swabian castles in terms of its layout, formal characteristics, and construction techniques, as it predates others built by Frederick II. Instead, it has undergone numerous transformations since the Angevin rule.
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.