Was the apostle Peter martyred in Rome?

You might have heard that the "Babylon" Peter refers to in 1Peter 5:13 is a code name for Rome as indicated in the writings of John in Revelation 18:2-3. This makes sense as the biblical Babylon was destroyed and desolated over 200 years before Peter wrote that letter.

Another clue about Peter being in Rome with Paul at some point is when he writes talking about what Paul writes to the Church like he was with him and had access to those writings in 2 Peter 3:14-16. Peter writes this letter when he was conscious he was going to die for Jesus as Jesus predicted when Peter was 40 years younger.

About Peter being a "Bishop" remember that Bishop comes from Greek and means "overseer". That's the exact duty Jesus entrusted Peter with! If Peter was in Rome at the end of his life like tradition and implicit Bible passages suggest, then saying that he was the first Bishop of Rome is not that far fetched.

The Bible does not mention Peter as ever going to Rome, and there is no early Christian record of this being the case. Even at the end of the first century, the author of 1 Clement appears unaware that St. Peter ever came to Rome. Although written from Rome, 1 Clement mentions Peter's 'many labours' and makes a general comment about Peter's death, without mentioning Rome:

There was Peter who by reason of unrighteous jealousy endured not one not one but many labours, and thus having borne his testimony went to his appointed place of glory."

George E. Demacopoulos (The Invention of Peter, page 21) says "the earliest surviving sources we have that place Peter in Rome" are the Martyrdom of Peter and the Acts of Peter. Rex Weyler, in The Jesus Sayings, page 252, says "Eusebius embellishes this report two centuries later by adding that both Peter and Paul were executed in Rome during Nero's persecutions, but he cites no source and gives an erroneous date, casting doubt on his research."

John W. O’Malley, S.J. says, in A History of the Popes, page 8, that "no one piece of evidence states in straightforward and unambiguous language either that Peter either went to Rome or that he died there." However, he relies on circumstantial evidence, particularly First Peter, which he sees as suggesting, or even indicating, by its reference to 'Babylon' that Peter is in Rome at the time the letter was written, which was probably about the year 63:

1 Peter 5:12-13: "I write you this briefly through Silvanus, 6 whom I consider a faithful brother, exhorting you and testifying that this is the true grace of God. Remain firm in it. The chosen one at Babylon sends you greeting, as does Mark, my son."

O’Malley acknowledges that 1 Peter was likely not written by Peter himself, although he believes it was written under his inspiration, but surprisingly overlooks that the reference to ‘Babylon’ is an anachronism before 70 CE*. This fact points to First Peter as pseudepigraphical, and without this letter, Father O'Malley has little more than Catholic tradition that Peter went to Rome or was martyred there.

Footnote

(*) Bart D. Ehrman says in Forged, page 68, scholars have long realised what the reference to ‘Babylon’ means in 1 Peter 5:13. Babylon was the city that had defeated Judah and destroyed Jerusalem and its Temple in the sixth century BCE. By the end of the first century Christians and Jews had started using the word Babylon as a code word for Rome, the city that was the enemy of God in their own day, which also destroyed Jerusalem and its Temple in the year 70. The author is claiming to be writing from the city of Rome, but using the code 'Babylon' is an anachronism during the lifetime of St. Peter.

Peter's Martyrdom in Rome

The first comprehensive history of the Church, undertaken by Eusebius in the early 4th century, states that Peter was crucified by Nero in Rome (Church History, Book II, Chapter XXV). Peter of Alexandria stated the same in one of his Epistles:

Thus Peter, the first of the apostles, having been often apprehended, and thrown into prison, and treated with igominy, was last of all crucified at Rome. Likewise also, the renowned Paul having been oftentimes delivered up and brought in peril of death, having endured many evils, and making his boast in his numerous persecutions and afflictions, in the same city was also himself beheaded.

Canonical Epistle, Canon IX

Lactantius, who lived during the 3rd century and later served as an advisor to Constantine the Great, also stated that Peter came to Rome during Nero's reign and was crucified by Him (Of the Manner in Which the Persecutors Died, Chapter II)

Prior to these writings, other Church Fathers attested that Peter was in Rome and that he was martyred.

Clement of Rome confirms that Peter was martyred in his 1st Epistle to the Corinthians, written in the late 1st century:

Through envy and jealousy, the greatest and most righteous pillars 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.

1 Clement 5:11-13

Irenaeus attests that Peter preached in Rome in Book III of Against Heresies, written sometime in the 2nd century:

Matthew also issued a written Gospel among the Hebrews in their own dialect, while Peter and Paul were preaching at Rome, and laying the foundations of the Church. After their departure, Mark, the disciple and interpreter of Peter, did also hand down to us in writing what had been preached by Peter.

Against Heresies III.I.1

Irenaeus also states in Against Heresies III.3.2 that the Church at Rome was co-founded by Peter along with Paul.

Hippolytus of Rome, a late 2nd/early 3rd century Church Father, describes a confrontation between Peter and Simon Magus in Rome subsequent to the account in Acts 8:9-24 in The Refutation of All Heresies (Book VI, Chapter XV)

Peter as Bishop of Rome

The Church Fathers do not seem to be perfectly clear that Peter held the actual office of bishop of Rome.

For example:

• Eusebius states, "After the martyrdom of Paul and Peter, Linus was the first to obtain the episcopate of the church at Rome" (Church History, Book III, Chapter II).

• Irenaeus similarly states that after the Apostles had "founded and built up the Church", they "committed into the hands of Linus the office of the episcopate" (Against Heresies, Book III, Chapter III). Neither Ireneaus nor Eusebius make it clear that Peter occupied the position of bishop himself before appointing Linus to the Episcopate.

• John Chrysostom states that Linus was the second bishop of Rome after Peter, but he qualifies the statement with "some say" (Homily X on 2 Timothy).

• Jerome, on the other hand, states definitively that Peter was bishop of Rome, though he is unsure of the succession of bishops immediately following Peter (Of Illustrious Men, Chapter 15). In the same work Jerome also states that Peter was at one time also bishop of Antioch (Ibid., chapter 16).

It is generally accepted that Peter was crucified upside down in Rome. Tertullian and Origen attest to this.

From WikiPedia:

According to the 1911 Catholic Encyclopedia, St. Peter labored in Rome during the last portion of his life, and there ended his life by martyrdom.[17] The death of St. Peter is attested to by Tertullian at the end of the 2nd century, and by Origen in Eusebius, Church History III.1. Origen says: "Peter was crucified at Rome with his head downwards, as he himself had desired to suffer."[17] This is why an upside down cross is generally accepted as a symbol of Peter, who would not have considered himself worthy enough to die the same way as his Savior.[35]

Whether or not Peter was bishop of Rome is still debated, although it is a belief held by the Catholic church.