Archeologists from the Danish National Museum have announced the discovery of a fifth Viking ring fortress. The fortress is located close to the modern day city of Koege, which is on the southern outskirts of Copenhagen. It is the second ring fortress found on the island of Zealand (the other being Trelleborg).
Following the announcement the archeologists involved have also stated that they expect to locate more ring fortresses in Denmark, and that several sites look promising. Additionally Swedish archeologists continue to investigate a possible Viking ring fortress close to Helsingborg, in Sweden (which would be the third, with the other two being Trelleborgen and Borgeby).
Undoubtedly these discoveries will in time help shed more light on the continuing debate about what the exact purpose of these fortresses was, and why they seemingly were abandoned again within decades of construction.
Source (in English): MedievalHistories.com