The original building dates back to before the year 1000, but only after 1100, thanks to the bishop Aldo, the temple acquired its final structure and importance.
The portico, supported by pillars decorated by precious romanesque capitals, dates back to this period.
The inside is divided into three naves, with final apses separated by pillars; firebrick is dominating. According to tradition the bishop Aldo was buried here, but his remains were never found. In his place were found the remains of Sant’Eufemia.
The church can only be opened by the janitor, it is open for Masses, and also open to visitors on appointment.