The ring fortresses

There are five ring-fortresses in Denmark and Skåne from the Viking Age – Trelleborg in Skåne, Trelleborg in Zealand, Nonnebakken in Funen and Fyrkat as well as Aggersborg in Jutland.

The building of the ring-castles must have required such immense resources as to be thought of as royal building works erected by King Harold Bluetooth. The period was characterized by turbulence and the king needed military bases from which he could control his possessions. Possibly the fortresses also served as centres for administration and trade.

The ring-fortresses were all built within a limited period of time around AD 980. The fortresses are not the only large installations which have been connected with royal power. Both bridges and roads – essential for transport on land – are known from the Viking Age. The Danish ring-fortresses differ from one another in a number of ways, but they are all constructed using the same measurements and geometric layout, with a circular rampart surrounding a block-like settlement. The symmetric place blocks are separated by ruler-straight streets.

The ring-castles were only used for a limited time before they were abandoned. It seems likely that after the death of Harold Bluetooth, Swein Forkbeard probably had a better grip on the internal political situation in the country – in that way the ring-fortresses were no longer needed as defensive installations.

Planer af tre militærlejre fra vikingetiden:
1. Trelleborg, 2 Aggersborg, 3 Fyrkat.