Up on the high, rolling plateau between the Rhine and the Lahn, where the Taunus fades into fields and beech woods, the Romans built one of the better preserved stone forts on the Upper German Limes. Holzhausen an der Haide is a quiet village of a little over a thousand people, and the fort sits just outside it in the trees, the outline of its walls still traceable on the ground, with the gates and corner towers marked out where the stone survives. It is part of the UNESCO-listed frontier that once ran from the Rhine near Koblenz all the way to the Danube, a line of palisade, ditch, watchtowers and garrisons meant less to stop armies than to control who came and went, and what they paid for the privilege.
Around the fort there was a civil settlement, the vicus, where soldiers' families, traders, tavern keepers and craftsmen lived off the garrison's pay. Nothing much of that stands today, but walking the perimeter you get a sense of how exposed this place was: a ridge of open country, wind coming over from the west, and the dark forest of the Germanic side not far beyond.
The riding up here is unhurried and genuinely pleasant. Small roads link Nastätten, Katzenelnbogen and the villages of the Einrich, as this corner is called, with long open bends across farmland and short wooded sections where the tarmac can stay damp well into the day. Traffic is light outside harvest time, when tractors own the lanes. Katzenelnbogen is worth the short detour for its castle above the village; the counts who took their name from it grew rich on Rhine tolls before the line died out in the fifteenth century. Further south the road down towards Bad Schwalbach drops through proper Taunus forest, all beech and spruce, with tighter turns and a few steep pitches.
For fuel, Nastätten is the nearest place you can rely on, and it also has bakeries and somewhere for a coffee. Bad Schwalbach, the old spa town with its mineral springs, is the bigger option if you want lunch with a terrace. Come in late spring or early autumn, when the fields are green or gold and the light lies low across the plateau; on a grey November day the place feels exactly like the edge of an empire, which, to be fair, is what it was.