Fyrkat is the Viking Age ring fortress located near Hobro in northern Denmark.
The fortress was built around 980 during the reign of Harald Bluetooth, when Denmark was being more firmly unified. Fyrkat consists of a circular earthwork with four gates arranged along two perpendicular roads. Four groups of longhouses were placed inside the ring, creating a highly regular plan.
Fyrkat is one of Denmark’s five known Trelleborg-type fortresses. The others include Trelleborg, Aggersborg, Nonnebakken and Borgring. Their precise layouts and substantial construction suggest organized royal authority rather than ordinary villages.
Fyrkat is sometimes confused with Aggersborg, the largest of the group, or Trelleborg, which gave the fortress type its modern name. Archaeologists have also found a nearby Viking Age cemetery and a richly furnished woman’s grave, adding evidence about the community connected with the fortress.