Augustenborg (German: Augustenburg) is a town with a population of 3,284 (1 January 2014) on Als Island in Sønderborg Municipality, Region of Southern Denmark in Denmark. The town lies at the head of Als Fjord. To the east is the Little Belt. Ferry service connects Augustenborg to the island of Funen from the nearby town of Fynshav.It was the main town of Augustenborg Municipality until its merger into Sønderborg Municipality in 2007.