Der Spiegel: The massive construction, called the Davevirke -- 'work of the Danes' -- is considered the largest earthwork in northern Europe... Archeologists have now taken a closer look a part of the construction -- a three-meter-thick wall from the 8th century near Hedeby... It is constructed entirely out of stones collected from the surrounding region...
The researchers have discovered the only gate leading through the Danevirke, a five-meter wide portal. According to old writings, 'horsemen and carts' used to stream through the gate, called 'Wiglesdor.' Next to it was a customs station and an inn that included a bordello. For a century, archaeologists have been dreaming of finding this gate between Denmark and Charlemagne's empire.
New calculations as to the age of the construction indicate, however, that the earliest parts of the wall might have been built by the Frisians and not by the Danes. Archaeologists now think the foundation stone might have been laid as early as the 7th century...
The Frisians, who lived on the west coast of what is now Denmark [and northern Germany] and on a number of islands in the North Sea, were fighting for supremacy in the region with three other peoples: the Danes, the Slavs and the Saxons... In the end, however, it was the Danes who emerged victorious. According to contemporary records, King Göttrik of Denmark ordered in 808 that the border of his empire with that of the Saxons be fortified.
But why make such an effort?... There was an Achilles heel in this far-flung trading empire, and that was at Hedeby. In order for goods from the east to be shipped to the west, they had to cross the narrow strip of land... For the duration of this short overland trek, the valuable goods -- including gold from Byzantium, bear pelts from Novgorod and even statues of Buddha from India -- were open to attack from the mainland... The Danevirke, in other words, was little more than a protective shield for commerce.