Refresh yourself for free by these public thermal fountains. It is fed by the hottest Burtscheider spring - the Landesbadquelle with 72°C.
Wikipedia https://de.wikipedia.org/wiki/Thermalbrunnen_Burtscheid
Address Burtscheider Markt 12, 52066 Aachen, Germany
Coordinates 50°45'47.902" N 6°5'32.159" E
