The oldest part is the Romanesque church and tower, which dates from the XII century. The church retains its original plain facade, go close and look, the facade contains some Roman tombstones which were uncovered when the building was constructed. Can you see the one to the left of the door? It reads, "Trophimus Daphidianus servo di Tiberio Claudio Cesare Augusto. Sacro alla Memoria Eterna"

The baptistery, next door, octagonal in shape, is built on the foundation of a fifth century structure, but dates from the sixteenth century and boasts some beautiful renaissance frescos.

Turning to my left I can enter this portico, which was added in the eighteenth century, creating an inner courtyard area. The baptistery and tower are behind me in this view.

This photo, taken a different day, shows the tower and Baveno's waterfront as seen from the lake, with the mountain of Baveno pink granite in the background.

And just who were Gervasio and Protasio anyway? They were brothers, Christian martyrs, who lived and died in Milan in the second century. They are patron saints of Milan, as well as of haymakers. This fourteenth century french manuscript drawing depicts their martyrdom.
Manuscript drawing Wikipedia.