It is not known with any certainty when Dill castle was built, but it is assumed that this happened in the 11th century, and that it might have been built on the ruins of an earlier Roman or Celtic complex.
At the complex's highest point, in the north, is the Oberburg (“upper castle”). Not much of the four-floor residential tower, whose sides measured 18 × 12 m, is left other than three outside walls; the east wall is missing. On the north wall's outer side is a garderobe. Parts of the barrel-vaulted cellar may still be visited. West of the upper castle, remnants of the girding wall have been unearthed. They exhibit a herringbone pattern in their construction.
On the area of the Niederburg (“lower castle” or “bailey”) to the east stand an Evangelical church, built on the spot where the castle chapel once stood, a wellhouse, which has been expanded into a holiday home, and a modern house.
Of the Vorburg (“forward castle” or perhaps “outer bailey”) to the west and south, only remnants of the foundations and outer wall can still be found. Part of the area is used as a garden.
The castle is in private ownership and normally cannot be visited. However, once or twice a year, there are guided tours. The times are published.
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.