Plombières-les-Bains owes its thermal reputation to a Roman discovery in the 2nd century, when a garrison accidentally discovered hot springs, guided by their dogs. Aware of the benefits of these waters, the Romans developed the first baths.

The true golden age of thermalism came in the 19th century with the rise of the railway, allowing Plombières to become a popular destination, notably thanks to the "Water Train" linking the town to Paris in less than six hours. Napoleon III, seduced by the town, modernized the infrastructure and had the prestigious Thermes Napoléon built, marking the peak of the spa town.

The waters of the resort are renowned for their effectiveness in treating digestive disorders, joint pain, Crohn's disease and fibromyalgia.