Château de Hac is a large castle built in the first half of 15th century. It has a rectangular main building flanked of five turrets. The present castle has not been altered much. The Gothic furniture and interior date from the 15th and 16th centuries. At the beginning of 15th century, it was the residence of the constable Arthur de Richemont and was the prerogative of the families of Richemont, Hingant, Tournemine and Rieux. There is also a medieval closed garden, tapestry of 16th century and stained glasses.
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.