His legend, according to the 14th century source known as the De laudibus Papiæ (In the Praise of Pavia), states that Syrus was the boy with the five loaves who appears in the Gospels.

As Hippolyte Delehaye writes, "To have lived amongst the Saviour's immediate following was...honorable...and accordingly old patrons of churches were identified with certain persons in the gospels or who were supposed to have had some part of Christ's life on earth.

"[1] Syrus is said to have followed Peter to Rome and from there he was sent to the Po valley to preach and convert the people to the Christian faith.

Syrus worked to challenge and convert those who followed Arianism in his diocese.

Bramante designed the chapel of San Siro in the city's cathedral, which contains the saint's relics.