The cathedral dedicated to the Assumption Mary was reconstructed in about 1120 on the site of a preexisting church dedicated to the Holy Mary. The Romanesque façade is interposed by the geometric intarsia marble framework of the main entrance added in the 13th century and attributed by Vasari to Nicola Pisano.
The interior was completely modified from 1580 – 1584 when Bishop Serguidi enthusiastically adhered to the new reforms laid down by the Council of Trent. Athough in late Rennaissance style, the cathedral still preserves the Romanesque latin cross and a nave flanked by two aisles.The columns dividing the nave from the aisles were decorated in stucco by Gianpaolo Rossetti and the capitals by Leonardo Ricciarelli.
The six altars framed by a sculptured frieze in Montecatini stone date to the beginning of the 16th century The gilded coffered ceiling, richly and colourfully decorated, was designed by Francesco Capriani, carved by Jacopo Pavolini of Castelfiorentino and gilded by Fulvo della Tuccia. The Holy Ghost in the centre is surrounded by the sculptured busts of saintsUgo, Giusto, Pope Linus,Clemente, Attinea and Greciniana and above the altar the Assumption Mary with saints Vittore and Ottaviano.
The baptistry erected on an octagonal base has been dated as 13th century although some architectural and decorative elements suggest that it was possibly built at an earlier date.The façade is adorned with stripes of white and green marble and the main entrance is surmounted by an architrave decorated with the sculptured heads of Christ, the Virgin and the apostles, a work of an artist
close to Nicola Pisano. It is said that Brunelleschi offered advise for the construction of the dome in the 15th century.
The interior still maintains an austere simplicity; the marble frieze framing the altar is the work of Mino da Fiesole and Alessandro Balsimelli from Settignano while the wood panel above the
altar of The Ascension was painted by Nicolò Cercignani in 1591. The baptismal font in the centre is by Vaccà (1760) while the octagonal marble baptismal font in the corner depicting the Baptising of Christ and the virtues of Faith,Hope,Charity and Justice was sculptured by Andrea Cuntucci , known as Sasovino in 1502
The 13th century Romanesque façade of St. Michael, extends to the entablature and bears the coats of arms of the Farnese family . In the lunette above the main entrance there is a copy of the original marble statue of the Madonna and child by a 14th century sculptor now in the Museum of Sacred Art. The interior was completely modified in the 19th century .