The site of Cuzorn, located in a bottleneck of the Lémance valley, allowed control of access to the region, but its origin remains unknown. The first mention of Cuzorn dates back to 1242, in the ruins of the Belleperche abbey, where an inscription mentions a certain B. de Cuzorn.
In 1259, the local nobility paid homage to the Count of Toulouse, including the brothers Gaubert, Pons, Guillaume, and Gaillard de Fumel, although neither lordship nor castle were mentioned at Cuzorn. However, documents from 1270 mention the lords of the castle of Cuzorn and Amalvinus de Cuzorn in conflict with the Bishop of Agen, suggesting a construction of the castle between 1260 and 1270.
Over the centuries, the lordship of Cuzorn had several owners, including the de Lézergues family and later the Gontaut de Saint-Geniès. In 1442, the castle was besieged, and later its defenses were dismantled. Subsequently, the lordship passed between different families until the 19th century.
In 1953, the castle was acquired by Georges Rastel, who undertook significant renovation work. In 1995, Thierry Delrieu became the owner of the castle, while the ruins were transferred to the municipality in 1996. In 1950, the castle was listed as a historical monument.
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.