In the apocryphal “Acts of Saints Nabor and Felix” (which are imitated from the Acts of other martyrs (such as those of Saint Firmus and Saint Rusticus), the two are said to be Roman soldiers from Mauretania Caesariensis serving under Maximian. They were condemned in Milan and executed by decapitation in Laus Pompeia (Lodi Vecchio).
In early 4th-century, their relics were translated, probably by the Bishop of Milan Maternus from their place of interment to a place outside the walls of Milan, placed a few hundred meters northwards the present Basilica of Sant’Ambrogio. A church (Basilica Naboriana) was built over their new tomb, as recorded by Paulinus of Milan in his life of Saint Ambrose. Tradition states that Savina of Milan died while praying at the tomb of Nabor and Felix. Saint Ambrose wrote an hymn about them.
When Emperor Frederick Barbarossa captured Milan in 1158, he gave some of the relics of Saints Felix and Nabor to Rainald of Dassel, archbishop of Cologne, who brought them to his episcopal see. The relics associated with Felix and Nabor are situated in a chapel in Cologne Cathedral. Nabor and Felix are depicted on the 1181 “Shrine of the Three Kings” by Nicholas of Verdun in Cologne Cathedral.
In 1258 their relics were moved to the church of Saint Francis of Assisi that was erected in place of the Basilica Naboriana. On 14-16 April 1798, shortly before the demolition of church of Saint Francis of Assisi, their relics were translated in the Basilica of Sant’Ambrogio. Their relics are placed today in an ancient sarcophagus in the Right-side nave of Sant’Ambrogio Basilica along with the relics of Saint Maternus and of Saint Valeria.