One of the four churches built at the direction of Saint Ambrose stands in the southeast of the city, on the ancient road connecting Rome and Milan. It was founded in 382-386 and dedicated to the twelve apostles, whose relic fragments were kept in the basilica at that time and are now preserved in the diocesan museum at the cathedral.
At the main altar of the church there is a reliquary with the relics of Saint Nazarius the Martyr. His body was discovered in 397, and at that time a new apse was built for it.
Today this church complex includes the Basilica of the Apostles, the Chapel of Saint Catherine, and the Trivulzio Mausoleum. Incidentally, the latter was built during the Renaissance by the famous Lombard artist and architect Bramantino.
