A 5th-century line of earthwork fortifications that cut across the base of the Jutland peninsula, forming the southern boundary of Viking Age Denmark (now in Germany). Timbers in its construction have been dated to about 737 AD, but these were likely replacement timbers, making the first building phase still earlier. It is puzzling archaeologically because the traces of only one large timber hall have been found, associated with enormous quantities of imported luxury items including a great deal of West European glass. Godfrey, king of Denmark who halted Charlemagne's march northward, began the construction of the Danevirke.