Augustenborg is a small town on the western shore of Als Fjord, built around the summer palace of the Augustenborg ducal line in the 18th century. The palace — a long, yellow Baroque building set in formal gardens above the water — now functions as a psychiatric hospital, but the grounds and garden are open to visitors, and the building can be viewed from outside. A small museum in the town covers the history of the duchy and the palace.
The waterfront below the palace is the nicest part of Augustenborg: a short harbour promenade with a marina and views across the fjord to the wooded far shore. The town itself is small and quiet, with a few shops and a church. It is a pleasant stop rather than a full destination — an hour is enough to see the palace grounds and walk the harbour.
The ducal line of Augustenborg had a significant role in 19th-century European dynastic politics: it produced consorts and candidates for several thrones, and the palace was the centre of considerable aristocratic activity before the 1864 war ended the duchy's political relevance. For visitors interested in the history of the Schleswig question — the contested Danish-German borderland — Augustenborg is part of the story alongside Sønderborg and Dybbøl.
Sønderborg is about 12 kilometres to the west.