Glücksburg Castle is a water castle, on the Flensburg Fjord in the town of Glücksburg, Germany. It is one of the most important Renaissance castles in northern Europe. It is the seat of the House of Schleswig-Holstein-Sonderburg-Glücksburg and was also used by the Danish kings. The castle is now a museum, and is no longer inhabited by the ducal family. It is owned by a foundation, which is headed by Christoph, Prince of Schleswig-Holstein, the current titular duke and head of the House of Glücksburg and House of Oldenburg.