Charlemagne chose Aachen for its hot springs, and the springs still bubble up under the old town, smelling faintly of sulphur at the fountains where they surface. Around the end of the eighth century he built a palace here and, at its heart, a chapel: an octagon under a dome, ringed by a sixteen-sided ambulatory, designed by Odo of Metz with columns and marble shipped from Ravenna and Rome. That chapel is the core of Aachen Cathedral, and in 1978 it became the first site in Germany on the World Heritage list.
Charlemagne was buried here in 814, and for some six centuries afterwards German kings came to Aachen to be crowned, climbing to the plain stone throne in the gallery that tradition links to the emperor himself. Later centuries added a soaring Gothic choir with walls that are almost all glass, so that the building now reads as two eras glued together: the dark, heavy Carolingian octagon and the bright cage of windows behind it. The treasury next door holds some of the most precious medieval objects in Europe, among them a bust reliquary of Charlemagne.
As a place to ride to, Aachen is a city stop, compact and walkable once you have parked. The centre has narrow lanes, pedestrian zones and plenty of traffic, and the cathedral sits right in the middle beside the town hall, itself built on the foundations of Charlemagne's palace hall. German low emission zones do not apply to motorcycles, which helps, but parking close to the cathedral is tight, so leave the bike at the edge of the old town.
The rides out are the reward. Vaals, across the Dutch border five kilometres away, sits at the foot of the Vaalserberg, where Germany, Belgium and the Netherlands meet and where the Netherlands reaches its highest point. South, the Eifel begins within half an hour, with the twisting roads around Monschau, the Rur reservoir and the high Venn moorland straddling the Belgian border. Weather in this corner shifts quickly between rain and bright sun, and the Venn can be foggy and cold when the city is mild.
Fuel, food and workshops are everywhere in a city this size. Do not leave without a packet of Aachener Printen, the spiced, hard gingerbread the city has baked for centuries, which keeps for weeks in a tank bag and improves every coffee stop.