South of Schleswig, in the narrow neck of land where the Jutland peninsula pinches itself between the Baltic and the North Sea marshes, lies one of the longest ancient monuments in Europe. This is the Danevirke, a system of earth ramparts, ditches and walls that runs for about thirty kilometres across the country, and the label here, Kovirke Area 7, refers to one of its sections, the Kovirke, whose name is usually translated as the Cow Work. Today the walls are grassy banks in fields, easy to miss if you are riding fast, but they once barred the way into Denmark.
The geography explains everything. The land between the Schlei, an arm of the Baltic reaching deep inland, and the marshy valleys of the Treene and the Eider on the west is only a few kilometres wide, and any army marching north along the old Army Road, or any herd of cattle driven south on the Ox Road, had to come through the gap. A wall there could shut the gate. The Danes knew it, and so did their enemies, and over many centuries the line was extended and rebuilt.
Today the area is a quiet agricultural landscape of fields, hedges and the odd farm. The roads that cross the line are small and gentle, running through villages such as Dannewerk and Fahrdorf, and the traffic is light. In 2018 the Danevirke was inscribed by UNESCO, together with the Viking town of Hedeby, as a World Heritage Site, so it is increasingly visited, and there are information boards and walking paths.
Schleswig is only five kilometres away, a town of twenty-four thousand, with fuel, supermarkets and plenty of cafés. Fahrdorf and Dannewerk are small but have a bakery or a pub. Walk along the rampart, which is easy underfoot, and think about the men who dug it with spades and baskets. It is a quiet, grassy place, and it rewards slow looking more than speed.