The history of Bagno Vignoni has been closely linked to the thermal springs on which this village was built since ancient times. Its waters were already used by the ancient Etruscans and Romans thanks to its excellent position. Thanks to the pilgrims passing along the Via Francigena , Bagno Vignoni became increasingly well-known. This location was visited by famous characters such as St Catherine of Siena, Enea Silvio Piccolomini, who became Pope Pius II, and Lorenzo the Magnificent. In the 16th century, Piazza delle Sorgenti was built: a pool from which the hot and steaming thermal waters still flow from the underground aquifer of volcanic origin. From here, the waters head towards the steep escarpment of the Parco Naturale dei Mulini (Park of the Mills), in which there are four medieval mills carved out of the rock. These were very important for the local economy, thanks to the thermal spring that ensured their functioning even in summer, when other mills in the area were not working due to the dried up rivers.