Viking shields were simple things
Viking shields were made from thin wooden planks and covered with leather. Some also had a metal rim to protect the edges. Round and flat, gripped at the domed metal boss in the middle. This meant that they could be maneuvered nimbly by movement in the wrist and held further out from the body than a strapped shield.
The design was by no means special or unique in its time. Many contemporary shield designs were very similar. There was however one difference; The Scandinavian shields were quite large. They tended to be bigger than their Ango-Saxon counterparts for example, who were otherwise identical. Why would that be?
Pictured is a an early and rather extravagant example, with metal fittings on the flat. And uncommon detail.