The thermal centre at Monsummano developed thanks to the chance discovery, in 1849, on the southern side of the mountain rising above the town, of a natural warm-steam cavern in a stone quarry owned by Domenico Giusti, father of the famous satirical poet Giuseppe Giusti. In July of 1853, after the first work carried out to adapt the cavern for use, the Giusti family began to exploit this new and unexpected resource. "The air of this cavern", wrote Antonio Targioni Tozzetti, who was the first to analyze it, "filled with steam and naturally heated to an appropriate temperature, offers an excellent means for taking steam baths, with great benefit to the health, as experience has clearly demonstrated." On the facade of the building leading to the cavern is a complex, elegant sundial made by Carlo Cataldi in 1898.

Today Monsummano Terme is one of the best-known anthropic therapy centres in Europe. The Museum of the City and the Territory has a section on thermal activity which documents the history of thermal baths in Monsumanno and the phenomenon of thermal tourism.