The first road stage of the Tour takes us from Düsseldorf, up the valley of the Düssel before turning around and heading west into Belgium for a sprint finish at Liège on the Meuse river. Along the way, we passed through Aachen, home of Charlemagne’s thermal baths.

The name Aachen comes from the Latin Aquae Granni, the “waters of Grannus,” a Celtic god of healing, which indicates that the hot springs were used by the native Celtic people before the arrival of the Romans. The facilities at Aquae Granni were expanded by the Romans.

A sketch of the Roman baths at Bücheltherme

According to his biographer Einhard, Charlemagne loved the hot springs at Aachen so much he built his palace there:

He enjoyed the exhalations from natural warm springs, and often practised swimming, in which he was such an adept that none could surpass him; and hence it was that he built his palace at Aix-la-Chapelle, and lived there constantly during his latter years until his death. He used not only to invite his sons to his bath, but his nobles and friends, and now and then a troop of his retinue or body guard, so that a hundred or more persons sometimes bathed with him.

Charlemagne oversees the construction of Aachen

The hot springs of Aachen are found in two very straight lines running southwest to northeast through the center of the city and through the suburb of Burtscheid. These lines of springs fall along outcrops of Upper Devonian Limestone that are pushed up to the surface by a pair of thrust faults (the Aachen and Burtscheid thrusts). Hot groundwater rises through these limestone layers to spill out in the springs.

A cross section of the rocks beneath Aachen. The blocky and spotted white layers are Upper Devonian limestone. From Herch 2000, Environmental Geology

A hot bath is probably just the ticket for Marcel Kittel and the other sprinters, not to mention the breakaway duo of Taylor Phinney and Yoann Offredo. Aachen is probably a bit too far away from Liège at this point, but nearby Chaudfontaine was called by Victor Hugo “la violette des stations thermales.”