The Lord built His Church on the foundation of the Apostles (Revelation 21:14). Today we celebrate two of the greatest of the Apostles, Peter and Paul. Peter, the Rock, was the chief of the Apostles, their leader and our first Pope. Peter was executed in the reign of Nero sometime between A.D. 64 & 67. There is no historical evidence for the tradition that he was crucified, either upright or upside down; but this is no reason to discount the tradition. His tomb was believed, since before the time of Constantine, to have been under what we now call the Vatican. In 1968 Pope Paul VI announced that the skeletal remains of St. Peter had been found beneath the high altar.
Paul, the Pharisee who was converted on his trip to Damascus was also executed in the reign of Nero, in A.D. 67 or 68. Possibly at the same time as St. Peter. The place of martyrdom in local Roman tradition is the site of the Basilica of St. Paul Outside the Walls. Since he was a Roman citizen, the mode of execution according to the same tradition was decapitation.