If you want to know what a Roman frontier fort actually looked like, this is the place. The Saalburg, on the ridge of the Taunus above Bad Homburg, is the only Limes fort in Germany rebuilt in full: walls, gates, towers, granary and the headquarters building, all standing again on their original foundations. The reconstruction was ordered by Kaiser Wilhelm II around 1900, who liked his Romans grand and imperial, and while archaeologists today debate some details, walking through the main gate is still a jolt.
The fort guarded a pass where an old road crossed the Taunus ridge, and it grew from a small earthwork into a stone fort for a cohort of about five hundred men, with a large civil settlement down the slope. The museum inside displays finds from the site and from the whole Limes, including shoes, tools and weapons, and the reconstructed buildings hold exhibitions and a café. Wilhelm's enthusiasm made the Saalburg the founding place of Limes research in Germany, and it remains the headquarters of that work today.
The road over the Saalburg pass, the B456 from Bad Homburg towards Usingen, is part of the attraction: a fast climb through forest with long, well-sighted bends. Riders love the whole Hochtaunus, and the Großer Feldberg, at 879 metres the highest summit of the range, is a classic meeting point a few kilometres west. That popularity has a downside: police checks and speed limits are frequent here, and weekend traffic on the ridge roads can be heavy. Come on a weekday, ride with restraint near the villages, and you will enjoy it far more.
For fuel, Wehrheim and Schmitten are close, and Bad Homburg and Oberursel at the foot of the hills have everything a rider needs. Bad Homburg's spa park and casino quarter are pleasantly grand for a coffee stop. Just north of the Saalburg, the Hessenpark open-air museum near Neu-Anspach has rebuilt villages of old Hessian farmhouses, a good companion stop if you are in a history mood. The beech forests on the ridge smell of earth and wet leaves even in summer, and from the fort's walls the view runs south over Frankfurt's towers, a reminder that the Romans' frontier is now commuter country.