Photo: Odense Bys Museer

"When I stand here at Nonnebakken, I find myself imagining how this great fortress must once have dominated the whole of Funen. I also think about the discoveries that still lie hidden and remarkably well preserved beneath the ground, holding the potential to reveal even more about the Viking Age if they are explored in the future."
Mads Runge, Head of Development, Museum Odense

Harald Bluetooth’s fortress by the River Odense

Nonnebakken is one of five known ring fortresses built by Harald Bluetooth as part of his ambition to unite and strengthen the Danish realm. With a diameter of around 180 metres, it was an impressive stronghold surrounded by a substantial rampart and strategically positioned beside the River Odense. Today, most of the fortress lies hidden beneath the modern city, which is precisely what makes a visit here so distinctive. The experience is as much about imagination as observation, inviting you to picture the vast fortress that once rose above the surrounding landscape.

Funen’s first UNESCO World Heritage site

Nonnebakken stands apart from Denmark’s other ring fortresses as the only one located within a modern city. Even in the Viking Age, it stood close to the growing settlement that would later become Odense, and the site played an important role in the city’s development. In 2023, Nonnebakken was inscribed on UNESCO’s World Heritage List alongside the four other Danish ring fortresses. The designation highlights its international significance and made Nonnebakken Funen’s first UNESCO World Heritage site.

The drama lies beneath your feet

Nonnebakken is just one chapter in the story of Viking Age Odense. Follow the trail to royal tombs, churches, ancient streets and other traces of the city’s Viking past. Download the Viking Route PDF and discover places where history can still be felt more than 1,000 years later.