Nonnebakken

Underneath the city of Odense lie the well-preserved traces of the Viking fortress Nonnebakken.

The five Danish ring fortresses, Aggersborg by the Limfjord, Fyrkat near Hobro, Nonnebakken in Odense, Trelleborg in Slagelse, and Borgring in Køge, have been inscribed on UNESCO's World Heritage List.

Archaeological investigations in 2015 and 2020 have shown that the fortress still lies extremely well-preserved beneath the modern city.

Nonnebakken was constructed around the year 980 and constituted a massive circular fortification with an outer diameter of 180 meters. Surrounding it was a moat at least 4 meters deep and 9 meters wide, along with a rampart, possibly up to 5-6 meters high and 15 meters wide, with wooden-clad fronts and backs. Each of the four cardinal points was equipped with a covered gate, connected by two axial roads dividing the fortress into quadrants. Within these quadrants were clusters of four longhouses, while a 1.6-meter-wide ring road ran along the inside of the rampart.

Nonnebakken is attributed to King Harald Bluetooth's ring fortress group, erected around the 970s-980s to strengthen the Danish realm and defend it against foreign threats. In addition to Nonnebakken, the group consisted of Aggersborg near Løgstør, Fyrkat near Hobro, Trelleborg near Slagelse, and Borgring near Køge. These fortresses all had a relatively short lifespan of only 10-15 years.

Nonnebakken derives its name from a convent established on the site in the 1100s. While parts of the fortress area are preserved beneath the modern city, including the flat fortress terrain where the Odd Fellow Lodge now stands, other parts remain hidden under the city's development.

Read more on the Museum Odense website: https://museumodense.dk/