Château or Donjon de Bours was most likely built in the 12th century by Hugues de Bours. Originally it would have had a bailey defended by a crenellated wall guarding several outbuildings. Both the bailey and the castle would have been moated. At present all traces of the bailey are gone.
Bours Castle is a keep built out of sandstone and has a rectangular plan with six corbelled turrets. It has walls of 70 cm thick and 2 floors. It is generally assumed that during the mid-13th century the keep would have been higher.
During the first half of the 15th century the castle was owned by Maillotins de Bours who restored and enlarged the castle but probably did not change the keep.
In 1543 Bours Castle was burned down.
At the beginning of the 20th century there was talk of demolishing the keep but luckily that did not happen. During the second half of the 20th century the keep was restored several times and used as a town hall.
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.