Archaeologists have discovered a perfectly circular Danish ring fortress in Borgring, Denmark, that dates back to AD 975-980.
The fortress is believed to have been built during the reign of Harald Bluetooth – the King of Denmark who is often credited with the first unification of the country.
The Borgring fortress is the first to be discovered in Denmark since 1953, and experts believe that there are many more to be identified around the country.
Researchers from Aarhus University discovered the fort using LiDAR technology, which revealed the tell-tale geometric outline of a ring fortress.
They then worked with experts from the University of York to use geophysics and radiocarbon dating of excavated timbers from a gateway to confirm the remarkable early medieval find.