Viking Fortress Trelleborg, Denmark

Danish Viking age Ring Fortresses declared UNESCO World Heritage Sites

Photo: Daniel Villadsen

Five historic Danish Viking age Ring Fortresses have just been added to the prestigious UNESCO World Heritage List. The fortresses were built between year 958 and 987 under the reign of the Danish Viking King Harald Bluetooth and are characterised by their remarkable symmetry.

The fortresses are some of the most prominent archaeological remains from the Viking Age in Denmark, while they at the time of construction testified to the ambition of uniting the Danish Kingdom and to protect it against external enemies.

“The Viking age holds a unique place in world history, and the Ring Fortresses are a physical manifestation from the time when Denmark was united as one kingdom and Scandinavia became a part of the Christian movement in Europe. Therefore, it is amazing – and with a good reason – that the Danish Ring Fortresses are now recognised by UNESCO as world heritage at the same level as, for instance, the Pyramids and the Great Wall of China. This decision will support the future research and communication about the Ring Fortresses – and hopefully, it will also contribute to attracting more visitors,” says Rane Willerslev, Museum Director of The National Museum of Denmark.

The five fortresses are spread across Denmark:


Aggersborg, located near Løgstør in Northern Jutland, is the largest of the Viking Age Ring Fortresses and was built around the 980s. The internal diameter of the fortress is 240 metre and was surrounded by a 9-metre-wide and approximately 4-metre-high circular rampart. The fortress has four gate openings, each pointing to the corners of the world, while timber streets are connecting the gates. Furthermore, a tower was built in the centre and surrounded by a total of 48 houses.


The fortress of Fyrkat near Hobro in Northern Jutland was built around the 980s. Still today, the rampart offers an impressive view. North of the fortress, a cemetery indicates that Fyrkat was inhabited by both men, women and children – furthermore, it indicates that this fortress might have been built to maintain royal power. Outside the fortress, you can today find a reconstruction of one of the largest houses. It is 28.5 metres long and built of oak.


Nonnebakken, which today is hidden beneath the modern city of Odense in Funen, was built around the year 980.  Due to its history and significant size, it is one of the largest and most important ancient monuments in the area. Nonnebakken (directly translated: 'The Nun Hill') was named after a nunnery located on the mound in the 12th century.


The fortress Borgring (in English: ‘Fortress Ring’) was strategically located in front of Køge Bay in Zealand. From here, all traffic in and around the East Zealand area could be controlled and monitored ideally from here. With an inner diameter of 121.50 metre  and ramparts about 10.5 metre wide, Borgring’s dimensions are very similar to the ones of the Fyrkat fortress. Borgring remains an archaeological mystery, and each summer, archaeologists visit the area to search for the secrets of the fortress.  

Photo:© Daniel Villadsen


The fortress of Trelleborg near Slagelse in West Zealand is located in the beautiful landscape of Tude Ådal. Through dendrochronological methods by dating timber from its moats, the fortress has been dated to around the year 980. Today, the remains of the great fortress can still be seen clearly, and visitors can explore the lives of the Vikings by visiting the reconstructed village of Slagløse.

Kathrine Lind Gustavussen

Denmark, International PR Consultant