German submarine U-37 (1938)

Sønderborg Municipality (Danish: Sønderborg Kommune, German: Kommune Sonderburg), is a kommune in the Region of Southern Denmark partially on the Jutland peninsula and partially on the island of Als in south Denmark, at the border with Germany. The municipality covers an area of 495.86 km2 (191.45 sq mi), and has a population of 74,380 (as of 2023). Its mayor as of 1 January 2014 is Erik Lauritzen, a member of the Social Democratic party.

Sønderborg station (Danish: Sønderborg Banegård or Sønderborg Station, previously Sønderborg H) is a railway station serving the city of Sønderborg in Southern Jutland, Denmark. The station is located on the west side of the Alssund, next to the Alsion science and culture centre. Sønderborg station is the eastern terminus of the Tinglev–Sønderborg railway line, which connects it to the Fredericia–Padborg railway line and the rest of the Danish rail network at Tinglev. The station opened in 1901. It offers frequent direct InterCity services to Kolding, Odense and Copenhagen.

Sønderborg (Danish pronunciation: [ˈsønɐˌpɒˀ]; German: Sonderburg [ˈzɔndɐbʊʁk] ) is a Danish town in the Region of Southern Denmark. It is the main town and the administrative seat of Sønderborg Municipality (Kommune). The town has a population of 28,137 (1 January 2023), in a municipality of 74,380. In recent times, Sønderborg is a center for trade, tourism, industry, and education in the region of Southern Denmark. The town is the headquarters for several industrial companies. Sønderburg joined the UNESCO Global Network of Learning Cities in 2016.

Sønderborg Castle (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.

Broager Sparekasse Skansen is a handball arena in Sønderborg, in Sønderjylland, which is primarily used for SønderjyskE handball home matches. The arena has a fixed stand with 1000 seats, as well as a long side stand that can be pulled out during handball matches, also with 1000 seats, so the arena has a total capacity of 2000 seats. The arena was built in 2012 in order to replace both Dybbølhallhallene and Humlehøjhallen arenas where they previously played their home matches. The arena is named after Broager Sparekasse which is a local bank that has financed a large part of the arena expenses.

The Alssund Bridge (Danish: Alssundbroen) is a 662-metre-long (2,172 ft) girder bridge that carries Highway 8 across the Alssund north of Sønderborg, Denmark. Constructed between 1978 and 1981, it was officially opened on 19 October 1981 by Queen Ingrid.

The Battle of Dybbøl (Danish: Slaget ved Dybbøl; German: Erstürmung der Düppeler Schanzen) was the key battle of the Second Schleswig War, fought between Denmark and Prussia. The battle was fought on the morning of 18 April 1864, following a siege that began on 2 April. Denmark suffered a severe defeat which – with the Prussian capture of the island of Als – ultimately decided the outcome of the war, forcing Danish cession of the duchies of Schleswig and Holstein.

The Alssund is the narrow strait between Als island and the mainland of Jutland, in Denmark.

Sandbjerg is a former estate and manor house 5 km (3.1 mi) north of Sønderborg in the southeast of Jutland, Denmark. The estate dates from 1571, but today's house was built in 1788. Since 1959, the estate has been used by Aarhus University for teaching and research. Today it is the university's conference centre.

Dybbøl is a small town with a population of 2,356 (1 January 2023) in the southeastern corner of South Jutland, Denmark. It is located around 6 km (3.7 mi) west of Sønderborg. It is mainly known for being the site of a famous last stand battle in 1864. During the Second Schleswig War in 1864, the Danish Army withdrew from the traditional fortified defence line, the Dannevirke (after waters and marshes which supported its flanks froze solid in a hard winter), and marched for Dybbøl to find a more defensible position. Although much artillery was abandoned and the evacuation was executed through a snow-laden north gale in winter, the army arrived almost intact. It entrenched itself at the Dybbøl trenches, which became the scene of the siege and subsequent Battle of Dybbøl (7 April – 18 April 1864). This battle resulted in a Prussian-Austrian victory over Denmark. In the following peace settlement, Denmark surrendered Schleswig. Following World War I, Denmark recovered the northern part of Schleswig as a result of the Schleswig Plebiscites as described in the Treaty of Versailles. The Dybbøl Mill is considered a Danish national symbol.