The church is wedged into the vast monumental complex that originally included the Convent and the Jesuit Schools.
Founded in 1602 and consecrated in 1620, it has an unfinished façade with four fluted pilasters of giant order framing a Serlian window. The façade is classicist, while the bell tower is Baroque, the style that predominates inside in the rich decoration and spaciousness of the single nave, punctuated by side chapels. Of particular interest is the altar of the Virgin, the last on the left, with two panels depicting the Martyrdom and Glory of St. Ursula (1652) by Luigi Miradori, known as Il Genovesino.

The central niche of the altar houses an elegant wooden sculpture of the Immaculate Conception (c. 1686) attributable to the Milanese sculptor Giuseppe Rusnati, while the wooden angels at the top of the altarpiece are by Giacomo Bertesi (1643-1710), who also created the spectacular wooden altarpiece of the high altar, which frames Gervasio Gatti's painting of Saints Marcellinus and Peter baptising Paolina (1604).
The presbytery celebrates the patron saints of the church, who are also depicted in the two side paintings (Saints Marcellino and Pietro helping the Cremonesi in battle and The transport of their relics), by Angelo Massarotti (1654-1723).
Rococo is also documented at the highest level with the high altar and that of St. Francis, the only marble altars in the church, both works by architect G. B. Zaist (1700-1757).