is the most ancient building of Castelseprio, the only survivor of the destruction and the abandonment of the ancient fortified village, thanks to devotion linked to the place of worship. The reason of main interest is still the original and amazingly preserved cycle of frescoes that decorate the compartment of the apse, among the most important witnesses of painting european masonry in the High Middle Ages.
Therefore belongs to the Carolingian age for period of construction, but to the Longobard one for ideal conception and for architectural continuity, which refers back to the Paleochristian basilicas of Milan of the IV-V century and that would be continued up to the XI century.
The church presents externally with a rustic simplicity, preceded by an atrium with a large arch, opened in the XVII century, while in the plant has a single rectangular nave, not very long, with an apse on each side over the input. The three apses are identical except for the layout of the windows. Outside they are reinforced by buttresses and covered by low sloping semiconici.
Inside the church had to be plastered and covered by frescoes and stuccoes, while the floor had reasons inlaid in marble. The church probably comes also the epitaph of Wideramn, rare testimony of the funerary culture written Lombard.
The ancient frescoes were spread themselves on the walls of the central apse, including side which gives to the Church, separated from the nave by a wall where it opens a round arch. The frescoes, found by chance in 1944, represent scenes of the infancy of Christ inspired, seems, especially to the apocryphal Gospels. Surprising is the compositional technique, which leaves the emergence of a sort of prospective scheme of direct classical ancestry, in addition to a clear realism in the representation of environments, human figures and animals. The cycle of frescoes thus testifies the permanence, late in the Longobard Age, of artistic elements classics of the survivors of the engagement of the Germanic conception of art, devoid of attention to the implications of perspective and naturalistic, and more concentrated on the symbolic meaning of the representations.