The Santa Maria Assunta cathedral was built between 1491 and 1501 on the site of the ancient parish church of Santa Maria and became an episcopal see dedicated to the Virgin of the Assumption in 1511.The exterior of the church is characterized by the structure with exposed bricks. Noteworthy is the central portal surmounted by a gothic gypsum in sculpted terracotta, flanked by two pillars that support the statues of St. Peter and St. Paul (1511).The two side portals are surmounted by lunettes frescoed with the figures of San Chiaffredo and San Costanzo, patron saints of the city and of the Marquisate.
The interior is divided into three large naves covered by ribbed cross vaults. Along the two aisles there are various altars, including the one dedicated to the Nativity, where the altarpiece with the Adoration of the Shepherds by Sebastiano Ricci is kept, and the one dedicated to the Saints Cosmas and Damian, or the oldest altar.In the central nave it is possible to see hanging a wooden crucifix dating back to 1400 and the presbytery is dominated by the grandiose machine of the high altar (1720).In the left side aisle the Chapel of the SS. Sacramento, where the sixteenth-century polyptych by Hans Clemer is preserved.