Archaeologists from The Danish Castle Centre and Aarhus University have made a sensational discovery south of Copenhagen, Denmark. On fields at Vallø Estate, near Køge, they have discovered traces of a massive Viking fortress built with heavy timbers and earthen embankments. The perfectly circular fortress is similar to the famous so-called ‘Trelleborg’ fortresses, which were built by King Harald Bluetooth around AD 980.
“This is the first time for more than 60 years that a new Viking ringed fortress has been discovered in Denmark,” explains Nanna Holm, an archaeologist and curator at the Danish Castle Centre. Her colleague on the excavation Søren Sindbæk, who is a professor of medieval archaeology at Aarhus University, adds “”The Vikings have a reputation as berserkers and pirates. It comes as a surprise to many that they were also capable of building magnificent fortresses. The discovery of the new Viking fortress is a unique opportunity to learn more about the battles and conflicts of the Vikings, and gives us a new chance to study the most famous of our Viking monuments.”
It was new, precise laser measurements of the landscape that led curator Nanna Holm on the trail of the fortress. An almost invisible rise in the field was shown to have a clear circular outline. Nanna Holm explains: “It is a huge monument. The fortress measures 145m from side to side. We recognize the ‘Trelleborg’ fortresses by the precise circular shape of the ramparts and by the four massive gates that are oriented at the four corners of the compass. Our investigations show that the new fortress was perfectly circular and had sturdy timber along the front; we have so far examined two gates, and they agree exactly with the ‘Trelleborg’ plan. It is a marvellous find. ”
Søren Sindbæk has researched Viking fortresses for years: “The discovery has been a piece of detective work. We suspected that one fortress was ‘missing’ on the island of Zealand. The location at Vallø was quite the right setting in the landscape: in a place where the old main roads met and reached out to Køge river valley, which in the Viking Age was a navigable fjord and one of Zealand’s best natural harbours. From there we worked our way forward step by step.”
Together the team called in Helen Goodchild, an expert in archaeological geophysics from the University of York, England, to carry out a more detailed, non-invasive, survey of the site, prior to excavation. Søren Sindbæk explains: “By measuring small variation in the earth’s magnetism we can identify certain archaeological features without destroying anything. In this way we achieved an amazingly detailed ‘ghost image’ of the fortress in a few days. From this survey we knew exactly where we had to put in excavation trenches to get as much information as possible about the mysterious fortress. ”
Nanna Holm stresses that the fortress was a real military installation, and probably also the scene of fighting. “We can see that the gates were burned-down; in the north gate we found massive, charred oak posts.” She also puts beyond doubt that the fortress belongs to the Viking age. “fortresses constructed in this manner are only known from the Viking Age. The burned wood in the gates will make it possible to determine the age by means of radiocarbon dating and dendrochronology. The samples have been sent, and we will be eager to hear the results. If we can establish exactly when the fortress was built, we may be able to understand the historic events of which the fortress was part.”
Viking fortresses are some of Denmark’s most famous monuments. They attract tourists from all over the world, and their study has repeatedly rewritten the history of Denmark. The previously excavated Trelleborg-type fortresses – Fyrkat, Aggersborg and Trelleborg – have been nominated for inscription in UNESCO’s list of world heritage sites.
For Vallø Estate, which owns the fields where the fortress was discovered, it has been a surprise to learn that there is a large archaeological site on their land. Director Søren Boas keenly supports the investigations. “This is a unique monument, which will be of great cultural value for Denmark. We are very happy to support it.” Keld Møller Hansen, director of the Museum of Southeast Denmark, which includes the Danish Castle Centre, hopes that funds can be gathered for a major research project in collaboration with the University of Aarhus.
The site may prove to be an important discovery in the Viking history of Denmark, says Nanna Holm. “We can’t wait to find out whether the fortress dates back to the time of Harald Bluetooth, or whether it was built by a previous king. A military fortification from the Viking Age may shed more light on the links between Zealand, ancient Denmark and the Jelling dynasty – as well as teaching us more about the period during which Denmark became Denmark,”
So far, only a small part of the fortress has been excavated. The list of unresolved issues is long, says Søren Sindbæk. “This is really exciting. A find like this does not happen many times in his life-time. The excavation has confirmed far more than we dared hope, but there is much more to learn. The next big question is whether there were large buildings inside the castle, as there are in the known Trelleborg fortresses. The find also raises the question as to whether there will be more new Viking fortresses to discover. The exploration will be a wonderful journey of discovery. ”
Sources: Aarhus University, Danish Castle Centre