Sønderborg Castle

The castle's origins date back to the 12th century when King Valdemar I ordered the construction of a fortress to protect against Wends. This southern castle, located on the island of Als, gave the burgeoning town of Sonderborg its name. In the 14th century, the fortress became the residence of Duke Valdemar V and underwent massive expansions from 1350 onwards. Under King Eric of Pomerania, the castle was the scene of military conflicts from 1410. Later, it served as the retirement home for Queen Dorothea of Brandenburg and, from 1531, became the prison for the deposed King Christian II. Under King Christian III and Duke Johann, the complex was transformed into a magnificent Renaissance residence. After the duchy's bankruptcy in 1667, the castle reverted to the Danish Crown and served as an administrative seat. King Frederick IV initiated Baroque alterations in the 18th century, including the removal of the tower spires and extensive fenestration. In the 19th and early 20th centuries, it served as a barracks and hospital before being converted into a museum after World War I.

Sonderborg Castle is located in the city of Sønderborg, in the Sønderborg district, in the Syddanmark region, Denmark, at an approximate elevation of 10 meters above sea level.

Today, the castle houses a museum dedicated to the history of Southern Jutland and Northern Schleswig, with a focus on 19th-century conflicts and the consequences of the World Wars. Many of the interiors are preserved in their original state and are accessible to visitors, including the Knights' Hall and the Renaissance castle chapel. Concerts of the Schleswig-Holstein Music Festival are regularly held in the Knights' Hall and the inner courtyard.

• Sandbjerg Slot (Castle), approx. 5.2 km away
• Augustenburg Castle (Castle), approx. 6.7 km away
• Gråsten Castle (Castle), approx. 12.3 km away
• Philippstal Manor (Manor House), approx. 13.1 km away