The Collegiate Church of St. Mary was built in the 12th century on a pre-existing early Christian church.
In 1494 it became square planned and had three naves with six octagonal columns. In the 16th century the side chapels were built with priceless Renaissance works such as the "Martyr Virgins", "St. Anthony the Abbot” from 1543 by the painter Jacopo Siculo and the "Miracle of St. Thomas” by one of his pupils. In 1560 the Collegiate Church of the Lateran Chapter was built.
The apse houses a panel depicting "Madonna with Child”, an 18th century Byzantine copy. Of considerable worth is the fresco in the arch of the apse featuring "God the Father enthroned among angels and two sphinx musicians” attributed to Giovanni Lo Spagna.
The white marble baptismal font is at the church entrance and bears a ritual inscription and a triangular panel representing St. John the Baptist in the upper frieze. The imposing 15th century bell tower spire still preserves the biggest bronze bell in the Valnerina valley, upon which the story of its destruction by the revolutionary Napoleonic troops in 1797 is reported.
