Rome is full of rich history of the ancient Church of Jesus Christ. While traveling around the ancient city, you can imagine what it was like after the death of Jesus Christ. The ancient apostles working as missionaries urgently working to spread the gospel and prepare the world for Christ to return again. Rome was in the center of the missionary work of the Apostle Peter.
Peter was the head of the Church after the Savior’s death and Resurrection, and there was a lot going on in the world! Peter had a huge responsibility and his taught and prophesied of the return of the Savior Jesus Christ.
Although, there are no scriptural records of Peter’s martyrdom, tradition says Peter died on a cross. Peter is said to have requested to be crucified upside down, because he did not consider himself worthy to die in the same way the Savior Jesus Christ did (see Joseph Fielding Smith, Doctrines of Salvation, comp. Bruce R. McConkie, 3 vols. [1954–56], 3:151–52).
Peter’s life was one of faithfulness.
In modern times he appeared to the Prophet Joseph Smith and Oliver Cowdery in Pennsylvania.
President Spencer W. Kimball (1895–1985) said of Peter: “With his loyal associates, James and John, Simon Peter returned to the earth, bridging the gap of darkened centuries. Together they appeared on the banks of the Susquehanna River in Pennsylvania, where Peter delivered to the young prophets the keys of the kingdom, which the apostles possessed from the Lord Jesus Christ” (Peter, My Brother, Brigham Young University Speeches of the Year [July 13, 1971], 8).
Tradition says the bones of Saint Peter, are laid to rest under the main altar of St. Peter’s Basilica. His tomb lies not far from his place of martyrdom in the Circus of Nero, where he was crucified upside down. The remains of the ancient cemetery of the Vatican hill still exist under the Basilica, with decorated tombs and Christian graffiti showing a very early date of veneration. Besides Peter, at least a portion of the relics of Thaddeus, (also known as Saint Jude) and Simon the Zealot are said to be at the Vatican as well.
Today, the city of Rome claims to be the final resting place of at least seven Apostles, although portions of these relics have been divided up among other churches worldwide.
Nero Claudius Caesar Augustus Germanicus ruled the Roman Empire from 54-68 AD, and hated the Christian. Nero is attributed for the deaths of the apostle Peter and many other Christians of the time.
The Church St. Paul Outside The Wall, is where many believe Apostle Paul was killed.
Reference:
https://www.christianity.com/wiki/people/how-did-the-apostle-paul-die.html