Very little remains today of the narrow Paleo-Christian church dedicated to Saints Protaso and Gervaso. Capitals and carved stone decorative motifs are still visible on the dividing wall that, for some, led to the parish house, and for others to a cloister (which, however, has never been discovered). The Paleo-church, built in the 8th century, was located adjacent to the current Sagrato area, that is, the cemetery. Excavations in the area have uncovered the remains of the demolished church and evidence of a probable medieval castle. The castle, built in a naturally defensible position and perhaps surrounded by a wide moat, overlooked the current Via Serbelloni and was adjacent to the sagrato. The internal simplicity, with a single nave in the shape of a Latin cross, its daring dome supported by 40 columns attached to the walls and four isolated ones sustaining the choir vault, certainly make it a remarkable monument. The church's interior features a fine apse vault with Renaissance rosettes above the main marble altar, and a small temple supported by six Corinthian columns that elevates the "Savior" sculpture at the top, modeled in gilded wood. The altar is completed by a bronze-doored tabernacle depicting the "Vision of Elijah"; two Carrara marble angels also stand out framing the altar. The vault interior houses four chapels with corresponding altars dedicated to other saints revered by the people of Gorgonzola. Notably, there is an oleograph portrait of Saint Charles Borromeo in prayer, by an unknown author, dated approximately to the 16th century. Of a later period is the painting of the Sorrowful Madonna, which, like the first, is displayed in the church sacristy. The church bell tower dates from a few years after the church's consecration, following numerous pressures and substantial bequests from wealthy local landowners to the church fabric committee: recognizing the centrality of the Gorgonzola municipality and pleban church, ecclesiastical and civil authorities committed to concentrating efforts to embellish the temple. This is how, in 1848, construction of the bell tower began, designed by architect Giacomo Muraglia (1791–1861), the same one who oversaw the church's completion and the hospital works.