The twelfth century church dedicated to Saint Michael, which was previously located on the site was converted into a convent between 1308 and 1318, when the Augustines of Santa Barbara al Bagnolo moved there. The friars were so attached to the Aldobrandeschi that, during the Sienese domination of Santa Fiora in 1381-1385, they favoured the return of the counts and contributed to the resistance. Over the centuries, the devotion of nobles and the population has enriched the church with a remarkable collection of sacred art, notably the great 14th century Crucifix and the Madonna by Jacopo della Quercia.