Located in Montorfano, a small hamlet in the municipality of Mergozzo, this Romanesque church is part of the Diocese of Novara. First mentioned in 885, the current granite building dates to the late 11th century. It features a cruciform layout with a single nave, ribbed vaults, a semicircular apse, and an octagonal dome topped by a square pinnacle. Decorative elements include blind arcades, carved capitals, and sculpted window frames, similar in style to the nearby Church of Santa Marta.
Excavations (1970–1984) uncovered remains of an earlier 8th–9th century church, medieval tombs, Roman-era structures, and a 5th–6th century early Christian baptistery beneath the current floor.