The Wetterau is one of the richest farming plains in Germany, a broad, fertile basin north of Frankfurt where loess soil lies deep over old river gravel, and wheat and sugar beet grow in enormous fields. At its edge the Taunus hills rise to the south and west, and the Roman Limes ran along their northern slope, taking in the whole plain as a deliberately protected frontier region. Watchtower 4/39 stands in this open country near Butzbach, and the number marks one of the many posts that kept watch over fields that were, even then, valuable enough to defend.
The tower itself, like most on the line, has been reconstructed or marked rather than preserved, and what the visitor finds is a good viewpoint on a gentle swell of ground. The wide horizon is its real attraction: the fields roll off in all directions, wind turbines turn slowly on the ridges, and in summer the larks sing so loudly overhead that you stop to listen. Butzbach, a few kilometres away, is a pleasant old Hessian town with a half-timbered market square, a handful of good cafés and a long history that includes a Roman fort and a medieval trading post.
For a rider the Wetterau is a gentle ride rather than a mountain road. Straight stretches between villages give way to a few lazy bends where the road follows a stream, and the traffic is mostly local, though the A5 motorway carries heavy lorry flows nearby and the main roads can be noisy. The surface is generally good, but beware of mud on the road at harvest time, and of low sun that makes the junction signs hard to read. To the south, the road climbs into the Taunus and becomes a different, twisty country.
Butzbach has all the usual services, including petrol, bakeries and supermarkets, and Langgöns and Rockenberg offer smaller stops. Spring, when the rape is flowering yellow, and early autumn, when the stubble is gold, are the best times. In midsummer the heat on the open plain can be heavy, so take plenty of water.