Les Monts Grantez is a fine passage chamber consisting of a passage of large, upright granite blocks and dry stone walling leading into an oval chamber. On the north side is a small side chamber. The passage and side chamber retain their capstones. It has been dated to the Neolithic Age (4000 - 3250 BC)
Discovered in 1839 it was excavated in 1912 by the Société Jersiaise. The main chamber was found to contain the skeletons of six adults and one child, all lying on their sides in a crouched position with quantities of limpet shells, bones and teeth of cow, horse, sheep, pig and deer and colourful sea pebbles. A further skeleton was found in a seated position, propped up by stones in the entrance passage and the scattered remains of a ninth individual in the side chamber. Three round bottomed bowls, broken vase supports, a clay spindle whorl, stone rubbers, hammers, a fine flint pick and a steatite bead were also found.
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.