Sønderborg Castle

Sønderborg Castle stands in the town of Sønderborg on the island of Als in South Jutland, set in a park overlooking Als Fjord in the middle of the town. This imposing castle carries around 800 years of history and has served in turn as a fortress, a royal residence and a prison - King Christian II was held captive here for many years. Today it houses Museum Sønderjylland, whose exhibitions focus on the history and culture of South Jutland, including the dramatic Schleswig Wars of the 19th century and the 1920 reunification, when the region voted to rejoin Denmark. Wandering the halls and towers, visitors move through centuries of border history that shaped this part of the country, and from the upper levels there are fine views over the water of Als Fjord. The museum is open year-round, making it a reliable stop in any season; adults pay 100 DKK while children enter free. The castle is closed on Mondays, so plan accordingly, and allow around two hours to take in the exhibitions at a comfortable pace. Getting there is easy - it is roughly a five-minute walk from Sønderborg railway station. For those interested in the region's military past, it pairs naturally with a visit to nearby Dybbøl Banke, the historic battlefield just outside town, giving a fuller picture of the events that defined the Danish-German borderland.