Built on a structure dedicated to Mercury and pagan cults. The first bishop of Como Felice changed the temple dedicated to a Christian church, in which he placed the mortal remains of Carpoforo. Located on the ancient Roman road connecting Como to Milan, the church of the 11th century shows a basilica plan with three naves interrupted by a transept nearly in the middle of their length. The eastern part is made up of a large apse with richly decorated walls, a crypt in the basement and two side apses; furthermore, over the presbytery, a raised roof made up a second pseudo-transept. Heavily altered during the centuries, the church was restored in the 19th century but it has not recovered the integrity of the original building.