Archaeologists are uncovering the mysteries of a Viking-age fortress at Borgring, on the island of Zealand in eastern Denmark, which is thought to have been built late in the 10th century by the Danish king Harald Bluetooth.
Until a few years ago, just four of these distinctive "ring forts" were known, located in different parts of the country. The remains of a fifth ring fort, at Borgring, were found in 2014 by archaeologists from Denmark's Aarhus University. It is the first to be found in more than 60 years, according to the researchers.
This image shows a 3D digital reconstruction of the northern gatehouse and rampart at Borgring, based on data gathered at the site by archaeologists. [Read full story about the Viking-age fortress]
One of the best-known Bluetooth ring forts in Denmark is at Trelleborg, on the island of Zealand.
Each of the ring forts built by Bluetooth in different parts of the country followed the same pattern of circular earthworks and wooden ramparts, with gateways at the four cardinal points of the compass. The gateways were connected by a crossroad paved with wooden planks.
Date of construction
A key discovery in this year’s excavations was a shaped plank of oak wood drilled with several holes. The researchers have not been able to determine what it was used for, but the tree growth rings in the oak have been used for dendrochronological dating.
The dating study shows that the plank was shaped from a tree felled after the 960s, which places the date of the construction of the Borgring fortress at the same time as other Bluetooth ring forts that were built in Denmark.