The church of San Gregorio Magno, Ascoli Piceno, began as a transformation in Christian place of worship of a Roman pagan temple, larger, that was built between the late Republican Age, the first century BC, and the first Augustan Age, The century AD in the area, behind the Palazzo Arengo, where it opens the Piazzetta di San Gregorio that connects the city plan to the Hill of the Annunziata.
The Corinthian temple, prostyle tetrastyle, was developed on a rectangular plan of 02.22 x 11.14 meters. Traditionally considered entitled to the goddess Vesta, in fact, according to Antonio Rodilossi, it seems to have been dedicated to the goddess Isis, as confirmed by an inscription found and that tells the fence dell’iseo.
In the late Middle Ages, the thirteenth century, the space of the existing temple, and what was left were enclosed by the Romanesque facade. For this purpose is reused large boulders and travertine left visible on the right side of the facade, perfectly integrated into the wall, the two Corinthian columns, of the four that were supposed to be there, the porch.
The church was dedicated to Pope Gregory I, who became St. Gregory the Great, as staunch supporter of the conversion of pagan temples into Christian churches. The image of the Pope is represented, within the classroom, near the deacon Peter together with an angel from heaven brings the inspiration of the “Dialogues”.