While the Cathedral of Mantua is dedicated to St. Peter the Apostle, the church houses the incorrupt body of St. Anselm, the bishop of Lucca and patron of the city and diocese, who lived in the 11th century.

The body of the saint is found inside the main altar. The image of Mary the Crowned is also venerated in this church.

The Duomo contains a rich collection of sculptures and paintings that decorate the cathedral, creating by several artists, including Andreasino, Teodoro Ghisi, Gerolamo Mazzola Bedoli, Domenico Fetti, Giambettino Cignaroli, Domenico Brusasorci, Giuseppe Bazzani and Felice Campi.

The exterior of the cathedral overlooks Piazza Sordello. In 1545 it was restored based on a design by Giulio Romano, which was inspired by St. Peter's Basilica of in Rome.

The Baroque style facade that appears today dates back to 1755 and was created by Nicolò Baschiera. However, the original medieval exterior was Gothic style, only traces of which remain on the facade.