Peter's death has been the subject of much tradition, myth, and speculation. The traditional account is that in 64 A.D. Peter was martyred in Rome on a cross upside down. There are no New Testament accounts of the date, the place, or circumstances of Peter's death, and no mention of an upside-down-crucifixion.

The only New Testament reference to Peter's death is Joh 21:18,19, where the account has Jesus saying to Peter:

When you were younger, you used to fasten your own belt and to go wherever you wished. But when you grow old, you will stretch out your hands, and someone else will fasten a belt around you and take you where you do not wish to go.” 19 (He said this to indicate the kind of death by which he would glorify God.) (NRSV)

The only New Testament mention of Peter even being in Rome is in 1 Peter 5:13: "Your sister church in Babylon ... sends you greeting." Babylon was a code-name for Rome. This was intended to represent Peter as writing from Rome, where tradition says he was martyred upside down. Many of the leading scholars today do not believe that 1 Peter (or 2 Peter) was written by Peter, but it does indicate that Christians in the second century believed Peter had visited Rome.

Clement was a first century Christian who was a co-worker of Paul. Tradition says he was ordained as Bishop of Rome by Peter. His known writings are included in the Ante-Nicene Fathers, writings by church "fathers" prior to the 325 A.D. Council of Nicaea, at which the Nicene Creed was formulated and became dogma. 1 Clem 5:1-6:1 refers to the First Letter of Clement to the Corinthians, chapter 5:1 to chapter 6:1. The passage from 1 Clement provides the earliest account of the martyrdom of both Peter and Paul.

But not to dwell upon ancient examples, let us come to the most recent spiritual heroes. Let us take the noble examples furnished in our own generation. Through envy and jealousy, the greatest and most righteous pillars [of the Church] have been persecuted and put to death. Let us set before our eyes the illustrious apostles. Peter, through unrighteous envy, endured not one or two, but numerous labours and when he had at length suffered martyrdom, departed to the place of glory due to him. Owing to envy, Paul also obtained the reward of patient endurance, after being seven times thrown into captivity, compelled to flee, and stoned. After preaching both in the east and west, he gained the illustrious reputation due to his faith, having taught righteousness to the whole world, and come to the extreme limit of the west, and suffered martyrdom under the prefects. Thus was he removed from the world, and went into the holy place, having proved himself a striking example of patience. To these men who spent their lives in the practice of holiness, there is to be added a great multitude of the elect, who, having through envy endured many indignities and tortures, furnished. us with a most excellent example.

Other early references to Peter's having been in Rome are in Ignatius' Letter to the Romans 4:3 and in Eusebius' History 2.25.8 (quoting Gaius, which account is at least questionable). It was Eusebius (History 3:1.2, quoting Origen) who also wrote that "Peter at the last came to Rome and was crucified head-downwards."