Borgring is the Viking ring fortress discovered near Køge on the Danish island of Zealand in 2014.
The circular fortress was identified through aerial laser scanning and later investigated by archaeologists. Its shape, large dimensions and construction methods linked it to Denmark’s other ring fortresses, including Trelleborg, Aggersborg and Fyrkat. Borgring is generally dated to the reign of Harald Bluetooth in the late tenth century.
The site is significant because it expanded the known network of monumental Danish fortifications. Researchers found evidence of gateways, defensive earthworks and settlement activity, helping compare Borgring with the better-known fortresses. Its position near important routes suggests that it may have supported movement, administration or military control.
Borgring is sometimes confused with Trelleborg because both are Danish Viking ring fortresses. Trelleborg was excavated and recognised much earlier, while Borgring became internationally notable after its modern discovery. The fortress is also known as Vallø Borgring, reflecting its location in the Køge area.