The aim of this short communication is to highlight how the improvement of health and quality of life through thermal water treatments is not only a highly sought-after practice today, but also one with a long-standing tradition in several European countries, including Spain, dating back to Roman times. The names of certain towns, such as Caldas de Reis and Caldas de Cuntis, bear witness to the natural wealth and the importance of mineral-medicinal waters as a strategic sector, both for tourism and healthcare purposes. However, this paper will not address the epidemiological, clinical, or therapeutic aspects of thermalism; instead, it will focus exclusively on its diachronic perspective.