Fürstliches Residenzschloß, in the center of the Detmold town park, is a fine example of Weser Renaissance style. In 1263, Bernard III of Lippe fortified the settlement at the crossing of the trade route from Paderborn to Lemgo over the Werre River with stone walls and granted it a municipal charter. In 1550, Detmold became the permanent residence of Count Simon III of Lippe. The counts were elevated to princes in 1789, and Detmold remained the capital of the small Principality of Lippe until the end of the World War I in 1918, when all princely states in Germany were abolished. Detmold Castle is still in the hands of the Princes of Lippe.
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.