The church was built by Pope Ormisda (514-523) over a large Roman bathroom created by the Emperor Caracalla. Major renovations occurred in the twelfth and fourteenth century, to get an idea of the changes you may find elements of the previous eras in the walls, such as a pointed arch and marble columns, and the door jambs made from Roman trabeations (horizontal beams). In 1440 the church came into the possession of the Savelli family some members of whom have been buried here, and the graves are visible inside the church. The interior has several frescoes from the Byzantine period of the XIII-XIV century and a sixteenth-century altarpiece depicting the delivery of the keys to St. Peter plus the banners of the eighteenth century. The Romanesque bell tower dates from the thirteenth century.