Built starting from 1592 on a project by the architect Raffaello di Zanobi da Fiesole, it was destined to become the seat of a new diocese removed from the intrusion of the Papal State.
Majestic sixteenth-century construction with a Latin cross plan and a Renaissance double-sided façade, which extends beyond the median frame of the tympanum, finished by two side vaults. Next to the facade stands the domed bell tower and, under its arches, the Baptistery.
The interior, in typical Renaissance style, has a single nave covered by trusses, bounded by a serrated frame and marked by four triumphal arches. The church contains numerous works of art: some paintings of the 16th-17th-18th century, an organ by Feliciano Fedeli from 1734 and a splendid sixteenth-century wooden crucifix of the Florentine school.
It is located in front of the Palazzo dei Commissari, as if to underline the two powers that regulate ordinary civil life.