The spa settlement, probably known since Etruscan times, was certainly used by the Romans as evidenced by the plaque, placed under the portico of St. Catherine’s church, consecrating these waters to the Nymphs.
Because of their proximity to the Via Francigena, an important route connecting northern Europe with the Italic peninsula, these baths were most popular during the Medieval period. Bagno Vignoni became a place of rest and refreshment for the many pilgrims who traveled via the Via Francigena to Rome, one of the main pilgrimage destinations of Christianity.
With the attendance at the baths, the village of Bagno Vignoni which became home to a pievana church. Beginning in the 12th century and continuing through the 13th century, the castle and baths were part of the lordly district of Tintinnano, belonging to the Tignosi family, and in the 1300s became the possession of the Salimbeni family.
As early as the 14th century, Siena was interested in Bagno Vignoni as evidenced by the “Relazione su lo Stato Senese” submitted to the Government of the Nine and written by Simone Tondi in 1334, which accurately describes the spa facility that: “is accommodated and surrounded by palaces and d’ostarie and has a chapel in the middle. It is of square figure all handsome, divided the fountain into two parts, which with the roof defends from the rain the sick, who bathe in it. But they are for all things places to be withdrawn where ascetic and guarded, men and women may bathe, the women’s bath being distinct from that of the males.”
Vignoni’s thermal waters were used both for personal hygiene and for the treatment of numerous diseases. For this reason it also became a place frequented by illustrious people, such as Pope Pius Il Piccolomini and Lorenzo the Magnificent.