La Sergenté is a Neolithic (4500 - 3250BC) passage grave leading into a circular chamber of diameter of 3.3m. The chamber walls are of dry stone construction and stand to a height of 75cm but originally would have risen to about 1.5m forming a vaulted roof. The fallen remains of this roof were found during excavtion in 1923. The chamber was paved with flat granite slabs except for a small partitioned off area on the west side.Parts of four, round bottomed, early Neolithic bowls, a few flint chips and fragments of charcoal were recovered during excavation. Though the style is unique to the Channel Islands this simple tomb is very similar to examples found in Brittany and Normandy.
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.