Sønderborg Castle built
1158 CE.
Shown on the map at 54.907°, 9.784°.
Sønderborg Castle (German: Schloss Sonderburg; Danish: Sønderborg Slot) is located in the town of Sønderborg, Denmark on the island of Als in South Jutland. It houses a museum focusing on the history and culture of the area. The castle is located in the middle of the town, in a park setting overlooking Als Fjord. The museum is open year-round.
Text from the Wikipedia article Sønderborg Castle, licensed CC BY-SA 4.0.