Saint Peter's tomb

The earliest reference to Peter's death is a letter from Clement, bishop of Rome, to the Corinthians in about AD 96. Eusebius, a contemporary of Constantine citing the earlier Origen, records that Peter "came to Rome, and was crucified with his head downwards", and Tertullian places the death in Nero's persecution of Christians.

Eusebius adds that the burial places of Peter and Paul were still known in his day, quoting Gaius, a Roman churchman writing early in the 3rd century against the Montanist Proclus: "if you will go to the Vatican or to the Ostian way, you will find the trophies of those who laid the foundations of this church." Catholic tradition holds that Peter was buried as close as possible to the scene of his death, in Christian-owned ground beside the Via Cornelia on the Vatican hill.

The mausoleum complex of the Vatican Necropolis dates from about AD 130 to AD 500. No mausoleum was ever built directly beneath the present high altar, but shallow burials lay there and later graves clustered round the space without encroaching on it. Around 160 a small niched monument was built into a wall there, the aedicula known as the trophy of Gaius.

Between 320 and 327 Constantine raised a five-aisled basilica over the necropolis, whose tombs were unroofed and filled with earth as foundation; it was consecrated by Pope Sylvester I in 326, with the altar set directly above the tomb. Whatever treasure stood at the tomb is presumed taken in the Saracen sack of 846. Gregory the Great later raised the presbytery, partly burying the Constantinian monument and creating the Confession.

Pius XI died in 1939 having asked to be buried at a particular spot in the Vatican Grottoes; lowering the cramped floor, the workmen exposed the cornice of a buried building. Pius XII ordered a scientific excavation, which ran from 1940 to 1949 under Monsignor Ludwig Kaas with the archaeologists Antonio Ferrua and Bruno Maria Apollonj Ghetti, without interruption through the Second World War.

The diggers broke through a stack of papal altars — Clement VIII's, Callixtus II's of 1123, Gregory the Great's — to the Constantinian Memoria Petri, and below the basilica a Roman necropolis used by Christians and non-Christians into the later 3rd century. At its centre was a grave cut in bare earth, set off by a wall of Christian graffiti naming Christ, Mary and Peter. Pius XII announced the find by radio in the Holy Year of 1950, while stating in December that year that none of the bones recovered could be confirmed as Peter's with absolute certainty.

A set of bones had been taken from a niche in the graffiti wall during the dig, without the archaeologists' knowledge. Accounts differ: by one, the basilica's administrator Ludwig Kaas, fearing the presumed relics would not be treated with the respect they deserved, had them stored elsewhere in 1942; by another, the foreman of the workmen gathered them from rubble left when the Constantinian casing was broken through. The epigrapher Margherita Guarducci traced the foreman and had the box handed over.

Venerando Correnti of Palermo University examined them in 1962 and reported a robust man of 60 to 70, with bones from every part of the skeleton except the feet; carbon analysis dated them to the first century. Guarducci, working from 1957 to 1969, read hundreds of graffiti on the wall and in 1965 reconstructed the Greek petros eni, "Peter is here". Antonio Ferrua, who had headed the excavation, said he was not convinced the bones were Peter's. On 26 June 1968 Paul VI stated that the relics had been identified in a manner considered convincing, on circumstantial evidence; the next day they were returned to their loculus in a plexiglass box, inscribed as bones held to belong to Saint Peter.

On 24 November 2013 part of the relics was displayed publicly for the first time, after Pope Francis celebrated the Mass closing the Year of Faith. On 2 July 2019 it was announced that Francis had transferred nine bone fragments to the Orthodox Ecumenical Patriarch Bartholomew of Constantinople, who called the gesture "brave and bold"; Francis said his decision was born "out of prayer" and was meant as a sign of the work towards communion between the churches. Most of the remains stay under the high altar of St Peter's Basilica. Modern scholarship holds that while the fragments cannot be conclusively verified as Peter's, the site was his original burial place, venerated for centuries before the first basilica rose over it.