 The settlement is mentioned for the first time in 714, when it was a possession of the Aldobrandeschi family.In 1252 it became a free commune, but lost its independence in the following century to the Republic of Siena, which entrusted it to powerful families like the Piccolomini and Salimbeni.Later, Castiglione was part of the Grand Duchy of Tuscany and, from 1861, of unified Italy.