A seasonal fishing hamlet since the Middle Ages, Christiansø fell briefly into Swedish hands in 1658, after which Christian V turned it into an invincible naval fortress. Bastions and barracks were built; a church, school and prison followed.
Christiansø became the Danish Navy’s forward position in the Baltic, serving to monitor Swedish trade routes, and in less congenial days as a base for attacks on Sweden. By the 1850s, though, the island was no longer needed as a forward base against Sweden, and the navy withdrew. Those who wanted to stay on as fishermen were allowed to live as free tenants in the old cottages. Their offspring, and a few latter-day fisherfolk and artists, currently make up Christiansø’s circa 100 residents. The entire island is an unspoiled reserve – there are no cats or dogs, no cars and no modern buildings – allowing the rich birdlife to prosper.