Rus 10th century shield, the Norwegian Gulaþing and Frostaþing laws specify the construction of a shield. The shield should be made of wood with three iron bands and a handle fastened to the back side by iron nails.
TRELLEBORGS, were viking ring fortresses, in Denmark, and Sweden. (Gatehouse) http://en.wikipedia.org/wiki/Viking_ring_castle
Viking Circular Bastion - Hobro, Denmark
trelleborg viking - Cerca con Google
The With of Trelleborg in Denmark by Jean-Claude Golvin