The church has a nave and two aisles, separated by octagonal columns with Romanesque capitals and round columns with Baroque capitals. It ends in large apses, and has a series of chapels opening into the aisles. The wall decoration is overwhelmingly Baroque. Other artworks include a choir by Matteo da Campione, the high altar by
Andrea Appiani, and the presbytery and transept frescoes by
Giuseppe Meda and
Giuseppe Arcimboldi.
Transects In a late Mannerist climate we are transported to the decorations of the internal heads of the transepts, starting with the southern one (Albero di Jesse, by Giuseppe Arcimboldi and Giuseppe Meda, 1558) to move on to the northern one (Stories of San Giovanni Battista, by G. Meda and Giovan Battista Fiammenghino, 1580).
Organs Inserted in the case in
Cornu Evangeli, it is a large 12-foot instrument in the
Italian Renaissance style but recently made, by the Italian firm Gustavo Zanin. Equipped with 17 stops and a single 54-note keyboard and an 18-note lectern pedal board. Placed in the old case in Cornu Epistolæ is the opus 617 from the prestigious Swiss organ manufacturer Metzler Orgelbau with fully mechanical transmission, with 29 stops distributed in the two manuals and pedal. It was built in 2002.
Presbytery The decoration of the presbytery and choir is the greatest pictorial achievement of the seventeenth century and sees Stefano Danedi known as Montalto, Isidoro Bianchi, Carlo Cane and Ercole Procaccini the Younger at work, with quadrature by Francesco Villa. The vault of the main nave was instead frescoed at the end of the century by Stefano Maria Legnani known as Legnanino, with squares by Castellino (1693).
Nave paintings The ten paintings in the central nave with
Stories of Theodolinda and the Iron Crown, made between the 17th and 18th centuries, belong to various painters, including
Sebastiano Ricci,
Filippo Abbiati and Andrea Porta.
Chapels However, it is above all the eighteenth century that marks the interior of the building, which constitutes a privileged observatory for the study of Lombard figurative culture between Baroque, Baroque and Rococo. Pietro Gilardi frescoes the lantern with Stories of the Cross (1718–19); Giovan Angelo Borroni paints in the chapel of the Rosary (1719–21), in that of the Baptistery and in that of Santa Lucia (1752–53); Mattia Bortoloni decorates the Corpus Domini chapel (1742). The final episode consists of the intervention in the cathedral by Carlo Innocenzo Carloni, the great master of international rococo, already active in Austria, Germany and Bohemia. Between 1738 and 1740, according to a program established by the Jesuit Bernardino Capriate, he decorated the vaults of the aisles, the triumphal arch and the western walls of the transept.
Treasury in the Theodelinda Chapel In the right transept is the entrance to the Serpero Museum which houses the treasury with the
Iron Crown of Lombardy, and the
Late Antique ivory
Poet and Muse diptych, of about 500, as well as an internationally important collection of late antique and early medieval works of various kinds, many deposited by Theodelinda herself. These include
small metal 6th century ampullae from the
Holy Land which are evidence of the emerging
iconography of medieval art, among them the earliest depictions of the treatments of the
Crucifixion and
Nativity of Jesus in art that were to become standard throughout the Middle Ages and beyond. Only
Bobbio has an equivalent collection of ampullae. The library holds a number of old and important
illuminated manuscripts. == Theodelinda Chapel ==