During World War II, the fort island was utilised by the German soldiers as part of the Atlantic Wall, which is when its additional military bunkers were constructed.

A remarkable sight
The unique fort is one of the largest of its kind and is now listed as a UNESCO World Monument. Some of its most interesting features include an impressive dining hall, a dungeon and an armoury. The island is often used for team-building excursions and it can be rented for parties and other events. It's also available for group tours by appointment. Smaller groups can visit the island on `public days' that are held on the first Sunday of every month between March and November.

In 2012, the attraction was awarded the Golden Green Key, becoming the first UNESCO World Heritage location to obtain a golden environmental label.