According to the founding tradition,[2] in 258, during the Valerian persecutions, the catacombs were temporarily used as place of sepulture of two other saints martyred in Rome, Peter and Paul.

[6] The building was refounded under Pope Nicholas I (858–867), while the martyr's altar was reconsecrated by Honorius III (1216–1227), by request of the Cistercians, who had received the place.

[7] The street which links Basilica of Saint Paul Outside the Walls with S. Sebastiano is still called "Via delle Sette Chiese".

The Chapel of Relics, located directly across the nave, houses a stone allegedly imprinted with the footprints of Jesus related to the episode of "Quo vadis?"

On the right side in a niche, the famous Bust of the Saviour (Salvator Mundi), the last masterpiece by Gian Lorenzo Bernini rediscovered in 2001 in the convent adjacent to the church, is shown.