Fishermen from Bornholm have used Ertholmene for temporary shelter since the Middle Ages. The first permanent settlement was the result of the Danish-Swedish conflicts in the late 17th century. As Denmark needed a naval base in the central Baltic Sea, a fort was built on Christiansø and Frederiksø in 1684 which served as an outpost for the Danish Navy until 1855. Christiansø Church originally served the garrison. The population peaked at the census in 1810 which showed 829 inhabitants. They were soldiers and were there because of the Gunboat War. Many of the historical buildings now serve as living quarters for the local population, and some are rented, year after year, to regular summer residents. The islands' external appearance has changed very little in over 300 years. Girdled by thick granite walls with old cannons pointed seaward, Christiansø is a picturesque tourist spot seemingly frozen in time. A former part of the fort, Store Tårn has housed the Christiansø Lighthouse for the past 200 years, and a small round tower on Frederiksø, Lille Tårn, serves as a museum.

When someday comes you'll need to get in.

When someday comes you'll need to be able to get around.