Heidenheim was first mentioned in the year 742. During that time the double monastery of Heidenheim am Hahnenkamm (housing monks and nuns), was founded by Saint Willibald and was later led by Saint Walpurga who became abbess after his death.
The first stone church was inaugurated in 778 and the next one hundred years later. The remains of current church date from the Romanesque style build constructed in 1182-1188.
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.