Sønderborg & Als

A small border town on the Als Sound, where Sønderborg Castle and the Dybbøl battlefield tell the story of the Second Schleswig War, surrounded by palaces, beaches and a science park.

Sønderborg lies in the southeastern corner of Denmark's Jutland peninsula, straddling the narrow Als Sound: the old town and castle are on the Als side, while the Dybbøl heights are across the water on the Jutland side, only about 40 km from Flensburg in Germany. In the Second Schleswig War of 1864, the Danish army suffered a crushing defeat at the Dybbøl fortifications, after which the area belonged to Prussia/Germany until a 1920 plebiscite returned it to Denmark, so traces of the two countries' intertwined history are everywhere in and around town.

The area divides into three parts: in town, the harborside promenade along the sound, the Kongevej pedestrian street and the castle museum can be seen in half a day; across the water, the Dybbøl Banke History Centre and the iconic Dybbøl Mill are essential for understanding Danish national memory; and on Als, the north has the Danfoss Universe science park, founded by the Danfoss group, and Nordborg Castle, the east has Augustenborg Palace, and the Kegnæs peninsula in the south has a lighthouse and beaches. To the west, Gråsten Palace on the fjord is the Danish royal family's summer residence, and farther west you can hike the Gendarmstien (Gendarme Path) or visit Frøslev Prison Camp.

The best time to visit is May–September, when the days are long and ideal for cycling and sea swimming; in early July there's the traditional ring-riding festival (Ringridning). Getting there: it's about 4 hours by train from Copenhagen (changing at Fredericia or elsewhere) and about 2.5 hours by car from Hamburg; Sønderborg Airport on the edge of town has flights to and from Copenhagen. The sights are spread out, so renting a car or cycling is recommended; plan to stay 2 days.

Top sights

• Sønderborg Castle – A four-winged old castle on the shore of the Alssund, first built in the 12th century. It now houses the South Jutland History Museum and o…
• History Centre Dybbøl Banke – An immersive history center on the site of the 1864 Battle of Dybbøl. Reconstructed fortifications, trenches, and cannon demonstrations rec…
• Universe Science Park – A science theme park founded by the Danfoss Group, with over a hundred hands-on exhibits, roller coasters, and outdoor water experiments. I…
• Dybbøl Mill – A white windmill destroyed twice in war and rebuilt, one of the symbols of Danish national identity, with views from the hill over Als Soun…
• Gråsten Palace – The Danish royal family's summer palace, a white Baroque palace beside the lake; when the royals are away, the gardens and chapel are open…
• Sønderborg Harbourfront & Kongevej – A harbour promenade along Als Sound links the castle, colourful old houses, restaurants and a city beach, with the pedestrian street Kongev…
• Augustenborg Palace – The white Rococo palace of the Augustenborg ducal family, with a large lawn in front and English-style gardens along the fjord; a quiet, el…
• Gendarmstien – An 84 km coastal trail along the Flensburg Fjord, once the patrol route of border gendarmes, certified as one of Europe's leading quality t…
• Frøslev Camp Museum – A detention camp set up in Denmark during the German occupation in World War II, with well-preserved barracks and watchtowers telling the s…
• Cathrinesminde Brickworks – A well-preserved 19th-century brickworks industrial site on the Flensburg Fjord, with a huge ring kiln and brick-making demonstrations.
• Kegnæs Lighthouse & Beaches – The peninsula at the southern tip of Als, where a white lighthouse stands beside the fields, with quiet beaches and campsites around it.
• Broager Church – A 12th-century Romanesque church known for its twin spires, a landmark for boats on the sound, with medieval murals inside.
• Nordborg Castle – A castle by the lake in northern Als, an 18th-century building on the site of a medieval castle, now a school; you can stroll along the lak…

Where to eat

• Syttende – A Michelin-starred restaurant on the 17th floor of the Alsik Hotel. In 2021 it became the first restaurant in Southern…
• Colosseum Restaurant – A family-run traditional Danish restaurant by the harbor, named Southern Jutland's best open sandwich in Opdag Danmark…
• Bistro Grand-Mère – A French bistro by the harbor known for 'grandmother-style' slow-cooked dishes, mussels with fries and red wine beef st…

Itineraries

• Denmark Grand Loop Self-Drive – A grand loop covering Zealand, Funen, Ærø, South Jutland, and Skagen, including three ferry crossings.