For anyone who likes to see how a frontier was really made, the East Wall of the Danevirke is a good place to stand. It is a long rampart running north-south across the base of the Jutland peninsula, a bank of earth and clay, with traces of timber and later brick, and in the section by Windeby you can see it as a low ridge across the fields. The Danes built and rebuilt it over several centuries, and it was one of the largest construction projects of the early medieval north.
The Danevirke guarded the narrow strip of land between the marshes of the Eider and the Schlei inlet, the only dry route between the Baltic and the North Sea. Whoever held it controlled the way into Denmark, and the king who owned it could tax the trade passing through the nearby port of Hedeby. The whole system, including the ramparts and Hedeby itself, is a World Heritage Site, listed in 2018, and the East Wall is one of its major parts.
Windeby, a small village two kilometres away, is better known for another find. In 1952 a body was found preserved in a peat bog near here, a young person who had died in the Iron Age, and for decades the so-called Windeby Girl was one of the best-known bog bodies in Europe, though later research changed ideas about the sex and cause of death. The find is a reminder of how deep the layers of history run in this quiet country.
The roads in the area are gentle and enjoyable. They cross low farmland, with hedgerows, red-brick villages and occasional glimpses of the Baltic, and the surface is good. There are no real hills, so the wind is the main feature, and in spring and early summer the rapeseed fields turn the whole land yellow. Eckernförde, a few kilometres east, has fuel, cafés and fish stalls, and it is the best place to stop.
Take a walk along the earthwork and read the information panels, which explain the building phases. An evening visit, when the sun is low, shows the contours better than a midday one.