The Petriolo thermal baths, also known as petriolo baths, are located in the Ombrone Valley, on the border between the province of Siena and the province of Grosseto.
Its waters flow out at a temperature of about 43 °C and can be used both freely and in any equipped establishments.
This Tuscan thermal spring has been known since ancient Roman times, even mentioned in an oration by Cicero, and some remains from both the Roman and Etruscan eras have been found near it.
The greatest prestige of the Terme di Petriolo was during the Renaissance era, so much so that both members of the Medici and Gonzaga families went there, as well as Pope Pius II.
