Aggersborg – The Giant Viking Trelleborg
Aggersborg is the site of a Viking trelleborg (ring fort), that was built near Aggersund on the north side of the Limfjord in Denmark.
A trelleborg was a geometrical circular fortification that usually contains a cross section of roads separating four internal quadrants, pointing in the four cardinal directions towards gated entrances.
Trelleborgs were built across numerous sites of strategic importance in areas of Denmark and Sweden, and are mostly attributed to Harold Bluetooth (a King of Denmark and Norway who ruled from AD 958–986), who was attributed with introducing Christianity to Denmark.
Aggersborg is Denmark’s largest trelleborg and dates from the Viking age between AD 970-980 (although archaeologists have also discovered that the fort overlaid an earlier Viking-Age rural settlement consisting of sunken huts connected with a couple of large farms), either during Harold Bluetooth’s reign, or that of his successor Sweyn Forkbeard.
The fort was strategically situated near a narrow passage of the Limfjord, a principal sailing route between the Baltic and the North Sea, and near the ancient Hærvejen trackway.