 Santa Fiora is mentioned for the first time in 890 AD, in a document listing properties of the Abbey of San Salvatore, Sforza Cesarini Archive Rome.By the eleventh century the lords of Santa Fiore were the Aldobrandeschi who, in 1082, started the construction of a castle here ("Castello S. Flore") and walled the "borgo".The power of the abbey passed by degrees to the Aldobrandeschi "conti di San Fire", and in turn to the hegemony in Lower Tuscany of the commune of Siena, which was strong influence on Santa Fiora by the mid fourteenth century, a future already foreseen by Dante