This is a fine example of Sienese Romanesque architecture. The church, designed according to a Latin cross plan, consists of a single nave with a simple gabled roof supported by wooden trusses. Inside, the oldest structre has been renovated, with the demolition of the baroque altars which had adorned it until the middle of the 20th century and the 15th century frescoes which partially cover the stone walls have been brought back to life. On the high altar was placed the altar piece depicting the Madonna with child and the saints Regina, Caterina and Bernardino (today moved to the right side), painted in 1635 by Astolfo Petrazzi; the wooden step with the tabernacle (today preserved in the Sacristry) of the same altar had been engraved and painted with the History of the Martyr, saint Regina, commissed in 1632 by the parish priest Girolamo Plamieri. 

Source: wikipedia.org