Gråsten is a town with a population of 4,365 on the east coast of the Jutland peninsula in south Denmark by the Nybøl Nor at an inlet of the Flensburg Fjord. It belongs to the Sønderborg municipality in Region of Southern Denmark. The town is located almost exactly at the center of a triangle defined by the towns of Aabenraa, Flensburg and Sønderborg Castle.

Sønderborg 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, 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.