Construction began in the 11th century of the original church on the site, which was consecrated in 1132.
It was demolished in the mid-19th century to make way for the current structure, which incorporates from its predecessor the mosaic floor of the presbytery and a chapel dedicated to Saint Syrus.
The present Neo-Classical cathedral was designed by the architect Alessandro Antonelli and was built between 1863 and 1869.
The baptistry, a separate structure although functionally part of the cathedral, is a Palaeo-Christian building dating from the 4th-5th centuries.
[1] The composers Pietro Generali, in the years leading up to his death in 1832, and Antonio Cagnoni, from 1879 to 1888, served as the maestri di cappella here.