Timeline

Heritage classified

Key figures

Origin and history

The Lédonia thermal baths of Lons-le-Saunier, built in the 4th quarter of the 19th century (1892-1894), are part of a thousand-year-old thermal tradition linked to the salt springs of the Jura. The city, formerly called Ledo salinarius ("the city of salt"), has been exploiting from the neolithic deposits of gem salt, a major economic resource until the 20th century. The thermal baths, founded in 1892, derive their name from the source Ledonia, one of the three sources of salt water (with Chavenay and Naparix) with recognized therapeutic properties, rich in sodium chloride and trace elements.

The project is led by Édouard Guénon, a rich resident of Lons-le-Saunier, who bequeaths an estate of 7 hectares to create a thermal park. The Parisian architect Jean Reboul designed the building, while landscaper Henri Michel (1854-1930) built the park, connected to the sources by underground pipes. Together, complete with a casino and a Bains station, forms a small spa town typical of the period, with separate galleries for men and women.

The waters of Lédonia, unfit for consumption in the state, are diluted for therapeutic uses: rheumatology, dermatology, or ORL. Ranked as historical monuments (falls and roofs in 1999, park in 1993), the thermal baths illustrate the golden age of French thermalism, mixing industrial salt heritage and architectural innovation. The site, owned by the municipality, today retains its original structure while adapting to modern practices.

Saliferous activity, which ceased in 1966, marked local history, with infrastructure such as the Salins-les-Bains saline or the Arc-et-Senans royal saline. The Lédonia thermal baths perpetuate this link between geology, medicine and heritage, while symbolizing the transition to a well-being and thermal tourism economy.

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