The Danevirke is the longest ancient earthwork in northern Europe, a system of ramparts, ditches and walls that crossed the narrow neck of Jutland at the base of the peninsula. Over several centuries, from the early Middle Ages into the twelfth, the Danes built and rebuilt it, closing the land route between the Baltic and the North Sea. Kovirke is one of its branches, and the section here, near Fahrdorf, preserves a piece of the bank that you can still see rising in the grass and the trees.
Tree-ring dating of timber found in the system points to a first major phase in the 730s, and later kings extended and strengthened it, culminating in a brick wall built in the twelfth century. It was a political statement as much as a defence, a way of saying that this was the border of the Danish realm. The Danevirke and the nearby Viking trading town of Hedeby were inscribed together on the World Heritage list in 2018, and they make a pair, the trade centre and the border.
The countryside here is quiet, low and open. Roads run between fields, through small villages and along the shore of the Schlei, with gentle curves and good surface, and the wind blowing over the flat land is the main thing to notice. It is not a thrill ride but a thoughtful one, best in the evening when the light slants across the earthworks and shows them clearly. Traffic is light except on the main road near Schleswig.
Fahrdorf is small, with about two and a half thousand people, and has basic services, but for fuel and a larger choice of restaurants you should head toward Schleswig, a short ride away, or to Kappeln on the Schlei, which has a good range of smoked-fish stalls. The Schlei herring is a speciality of the area.
Wear sturdy shoes for the walk, because the paths can be muddy, and bring something to read the information boards, since the earthworks look like low hills until someone points them out.