Christiansø is a small island located in the Ertholmene archipelago near Bornholm. Its name refers to the name of the King of Denmark and Norway, Christian V Oldenburg. Tourists may come to Christiansø by a ferry, boat or yacht. The harbor is located in a small sound between two islands – Christiansø and Frederiksø – spanned by a 30-meter bridge. Round stone Store Tårn, i.e. Big Tower, is the landmark of Christiansø that has been operating on the island for years as a lighthouse.