An earthwork is a good place to watch birds, and the grassy banks of the Danevirke are better for wildlife than the intensive fields on either side. Here the ramparts have been left as pasture and rough grassland for centuries, so they have become a long, narrow nature reserve, a green corridor through the farmland. In summer the banks are alive with butterflies, grasshoppers and bees, and in the evening bats flicker along the hedgerows. Skylarks and yellowhammers sing from the fence posts, and kestrels hover over the open ground.
This section, labelled Kovirke Areas 3 to 5, runs through the country near Dannewerk and Kropp, in the middle of the system. The wall is lower here than in some places, worn down by ploughs and weather, but the ditch is still easy to see, and the line runs straight across a gentle slope. It is a place to get off the bike, walk for ten minutes, and listen. The sound of the wind in the grass is quite different from the noise of an engine.
The ride is gentle, along tidy country roads between fields of maize and wheat, past farms with red-brick barns and the occasional thatched roof. The surfaces are good, the junctions are sparse, and the traffic is mostly local farmers and cyclists. Come early in the day for the best light and the most birdsong, and avoid harvest time, when slow combine harvesters can hold you up for miles. After rain, tractors leave mud on the road, so watch for slippery patches at the field entrances.
Dannewerk is two kilometres away and is the village that gave the whole monument its name, with a little museum, a church and a few farms. Kropp, a town of six thousand, is the sensible place for fuel and food, and Schuby is another option. Bring a rain jacket, because the weather on the plain changes quickly. A small flask of coffee makes the walk along the bank a pleasure. It is an easy place to spend an hour.