The first news about "Bagni di Petriolo" go back to 1230. In the month of June of that year, Siena Municipality sent the notary Bonfilio to make the list of the people "qui iverant ad balneum". In his description of Italy, Leandro Alberti says that the Baths, which Marco Tullio Cicerone spoke about in his oration in favour of Marco Caelio are those of Petriolo and that about the same Baths spoke also Marziale in his epigrams. The recent discovery of Roman graves near Petriolo is a proof of this.

In 1404 the Petriolo Thermal Baths were fortified and this is the only example left of the fortified thermal baths. Today we can still admire their walls and the Tower of the Sienese Republic. Famous, thanks to the curative properties of their sulphureous water, Petriolo Thermal Baths were attended by many famous people. Among them, there were members of the Medici and Gonzaga families, cardinals, dukes and an excellent customary visitor, Pope Pius II - Enea Silvio Piccolomini. Petriolo is one of our prefered thermal spas. Not too far away, on the road to Siena, we often make a stop there, especially in Winter. The Hotel "Therme di Petriolo" we leave aside and go down to the river Farma where you find small rock bassins. The sulphur water is very relaxing and after the bath you can take a dip in the river.