Located in present-day Germany, the Dannevirke Wall (“the work of the Danes”) was for centuries the border between the Danes and Germanic peoples to the south. Actually Dannevirke is a patchwork of earthwork walls running east to west 30 kilometers across the Jutland peninsula. The foundation of the first wall goes back to the 7th century, and since more sections were added and existing walls expanded and repaired. There is mention of such work both during the reign of King Godfred c800, and again during the reign of Harald Bluetooth in the mid-10th century.
Being a defensive work, then there were very few gates (as these would be weak points, and opportunities for attack). However, increasingly it is also understood that besides serving as a border demarcation, then Dannevirke also served as protection of an overland trade route across the Jutland peninsula. On the east side, the renowned trading of Hedeby was actually incorporated into the Dannevirke sections. The alternative to bring goods across this narrow piece of land and then re-shipping it into the Scandinavian and Baltic Sea basin, would have been to sail it around Jutland – which with sail ships would have been a significant increase in travel time.
It was with a great deal of excitement that in 2010 it was announced that one of the few gateways had been located. Excavation of the Wiglesdor gate was started, and has been progressing since. Here is a link to some more recent pictures from the excavations: http://www.wikinger-in-daenemark.de/wiglesdor/Wiglesdor-1.htm. Now all that is left is to patiently await analysis and conclusions from the findings!
Source (original 2010 announcement): Spiegel.de