‘Kovirke’ which is 6.5 km long was built in 808. The rampart was built with huge oak poles about 4 meters long which were dug into the earth. It was 1.86 meters between each pole so calculations show there must have been 3500 poles. Crosswise between the the poles were planks which held the earth. These planks functioned as a chest protection for the warriors. Diagonal poles kept the whole thing in place.
It has been calculated that for this rampart 12,000-14,000 oaks must have been used. A whole forest! The earth for the rampart came from the rampart diggings – 40,000 m3 in all. Other measurements can be seen on the drawing (Illustration after Helmut Andersen: Jyllands Vold, 1977.)
Nobody knows how many men worked on the ramparts. Indications are that it was a rush job. Probably 2000 men could have built it in a month.