The Basilica of San Nazaro in Brolo (as it is also known) was founded by Sant’Ambrogio between 382 and 386 AD along the road from Milano to Rome. It was initially dedicated to the Holy Apostles as, seemingly, fragments of cloth that had come into contact with the bodies of the Saints buried in Rome are preserved herein. Due to its ancient origins, it represents one of the main examples of paleo-Christian art in the city.
The remains of the martyred San Nazaro were found in 395, so Sant'Ambrogio modified the dedication of the church to preserve them in the edifice. According to legend, persecuted by the emperor Nero, San Nazaro was beheaded together with the young disciple Celsus in Milano, in a location called “Tre Muri” (Three Walls) in the Porta Romana district. For fear of the emperor’s wrath, the Christians immediately stole the bodies to bury them in a secret place which, centuries later, the Lord revealed to Ambrogio.
The body of Celsus was left where it was discovered - where the basilica thereafter dedicated to him is located (Corso Italia) and where the relics are kept - while the remains of Nazaro was brought to the basilica.
The church façade, however, is very different from what one might expect: it is not in typical Romanesque style often seen in Milano. In 1512, construction began on the Trivulzio Chapel, the only documented architectural work by Bramantino in Milano. Created as a mausoleum for the family of Gian Giacomo Trivulzio, marshal of the King of France, Louis XII, it is attached to the Paleochristian façade like a sort of access vestibule to the church.
- In the Trivulzio family chapel, Giangiacomo Trivulzio’s tomb lies between those of his two wives. An inscription in Latin on the memorial plaque is translated by some historians into Milanese: "Lè staa mai cont i man in man" (He has never been idle).
- Descending to the right of the presbytery, visitors enter the small archaeological area where the Roman amphorae and bricks, plus, tiles with animal paw prints are conserved, most probably material left to dry before firing that had accidentally been stepped on by the beasts.