The interior is designed on the
Latin cross plan, with the nave containing a central aisle and two side aisles, and houses works by
Macrino d'Alba,
Bernardino Ferrari and others, as well as a
tempera polyptych of the school of
Leonardo da Vinci. In the chapel of St. Charles or of the Blessed Sacrament, two other recently restored works by the painter from Vigevano are preserved: the
Gusberti Triptych and a
Saint Thomas of Canterbury between saints Helen and Agatha. The
Madonna with Child between Saint Bernardino, Saint Clare and the Blessed Cristoforo Maccasoli, dated 1502 but unsigned, comes from the convent church of Madonna delle Grazie near
Paragella, destroyed in 1805. It is attributed to the Piedmontese Renaissance painter
Macrino d'Alba; although it does not present the chromatic liveliness of the polyptych of the
Certosa di Pavia, it shows a certain analogy with this one. The panel with the
Crucifixion and saints is one of the few works dated and signed at the bottom right "CAESAR MAGNUM FACIEBAT AN 1531" by the painter
Cesare Magni, follower of
Leonardo. It was donated by Duke
Francesco II Sforza as shown in the deed of donation dated 13 March 1534 in the Capitular Archives. Above, the earthly Christ is surrounded by flying angels. On the left the Virgin in a bright red robe and blue mantle, while Saint Ambrose in pontifical vestments presents the Bishop
Galeazzo Pietra in an arabesque cope. On the right, Magdalene in a blue dress and red cloak, Saint John and Saint Jerome, with a thick beard. In the background, countries, figures and knights fading into blue. An interesting painting from the 16th century in Lombardy is the
Redeemer on the Globe with the Madonna and Saint John the Baptist, attributed to
Bernardino Gatti (ca. 1495/ 1576), known as Soiaro. The funerary monument of Galeazzo Pietra, first bishop of Vigevano from 1530 to 1552, of a Pavia workshop, was built by the hand of a Bernardo Romano, probably a close relative of Cristoforo Romano. Previously located in the presbytery, it was moved during the restorations of 1828/30 with the addition of the stone between the sarcophagus and the inscription. The nineteenth-century painter
Francesco Gonin chose light colors and gilding for the frescoes on the vault, which depict the life of
St. Ambrose, to whom the cathedral is dedicated. Also of great interest is the pipe organ located in the presbytery, in the right choir, built in 1782 by the
Serassi of Bergamo. ==Treasury==