In Catholic tradition , St. Peter 's Basilica is believed to be the burial place of Saint Peter , who was one of the twelve apostles of Jesus . In Catholic tradition , the basilica is the burial site of its namesake Saint Peter , who was one of the twelve apostles of Jesus and , according to tradition , first Bishop of Rome and therefore first in the line of the papal succession . Tradition and some historical evidence hold that Saint Peter 's tomb is directly below the altar of the basilica .