STRUCTURE

The 5th century building, 36m long and 32.5cm wide, had a Latin cross plan whose arms ended with apses, following the architectural model derived from contemporary examples in Milan, in particular the Basilica Apostolorum, today San Nazaro in Brolo. The apses of the main axes were polygonal on the outside and semicircular on the inside, while those of the north-south transept were semicircular and characterised by buttresses. The main entrance, which had an atrium in front of it, opened towards the west. In the 9th century the church was rebuilt in a rectangular shape with a single nave and markedly smaller in size, closed to the east by a semicircular apse built on the remains of the preexisting one, while to the west there was a small atrium in front of it with funerary functions. Two centuries later the building was lengthened by 5m in a western direction while the southern apse was kept, used as a crypt and subsequently transformed into a cellar in the late Middle Ages. The southern side has also kept the bases of three columns which supported a portico, evidenced by a painting held in Saint Ursus dating from 1514.
Further modifications were carried out during the Late Middle Ages and the southern International Gothic portal dates from the 15th century. The most recent works, which saw the entrance moved to the eastern side and gave it its present-day appearance, date from 1642.