The history of Krageholm estate date from the 14th century when it was owned by family Due. Later in Middle Ages it was moved to Tott and Brahe families. In 1642 it was given to Otto Marsvin. The estate was damaged in the war with Denmark during the reign of Carl XI. In 1704 the estate was sold to Carl Piper. The present appearance was built in 1720s. The main building and two annexes are surrounded by moat and park.
St. Paul's Chapel, designed by Tessin the Younger, housed in the east wing, was opened in 1723. Since then, Krageholm been in the family Piper's possession with the exception of 1897-1930 when the last of the Brahe family held the estate.
There are two runestones from the Viking Age in the castle park near the southern entrance.
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.