With its triangular floor plan, Wewelsburg Castle occupies an extraordinary position in German architectural history. The castle, which was completed in 1609, incorporates a medieval tower structure. An inscription above the main portal indicates the intentions of its builder, Paderborn's Prince Bishop Dietrich von Fürstenberg: to assert the interests of sovereignty and realize the aims of the Counter-Reformation within his territory. The dilapidated state of the building in the 19th century inspired Schinkel's proposal to transform Wewelsburg castle into an artificial ruin, and Annette von Droste-Hülshoff was moved to make it the subject of some of her ballads. In the Weimar Republic, the Catholic youth movement held interregional events here. In the "Third Reich", Heinrich Himmler pursued extensive plans to convert the castle into an ideological center of the SS. 1285 prisoners of a specially established concentration camp were murdered during construction. The SS blew up the building in 1945, causing extensive damage. Today, the reconstructed Wewelsburg Castle has resumed its pre-1933 function as a youth hostel, and it is the home of the Historical Museum of the Prince Bishopric of Paderborn. The neighboring guardhouse accommodates the permanent exhibition "Wewelsburg Castle 1933 - 1945, Cult and Terror Center of the SS", which is also a memorial for concentration camp victims. It will be reopened with a new concept in 2010.