London (CNN) -- After centuries buried beneath the Vatican, and decades hidden away inside the Holy See, the bones of a man long believed to be St. Peter, one of the founding fathers of the Christian church, are on display for the first time.
The controversial remains were revealed to the public on Sunday at a mass in St Peter's Square marking the conclusion of the Catholic church's "Year of Faith."
Writing in L'Osservatore Romano, the semi-official Vatican newspaper, Archbishop Rino Fisichella said the "relics which tradition recognizes as those of the apostle who gave his life for the Lord" would be exhibited as part of the service.
L'Osservatore Romano reports that 8.5 million pilgrims have venerated the relics over the course of the year.
But whether the bones, normally kept in an urn housed in the private chapel of the Pope's own Vatican apartments, really are those of St. Peter, the fisherman-turned-disciple who became the first pope, is open to question.
Tradition has it that St. Peter was martyred -- by being crucified, upside down -- in Rome in A.D. 64. before being buried in the city.
In his book "The Vatican Diaries," John Thavis wrote that "St. Peter's tomb in the cemetery on the Vatican Hill became... a popular pilgrimage site," prompting the emperor Constantine to build a basilica in his honor in the 4th century.
The remains which will be revealed on Sunday were among those discovered during an archaeological dig begun on the site in 1939; in 1968 the then pope, Paul VI, declared that they had been identified "in a manner which we believe convincing."
But with no DNA evidence to conclusively prove their identity, whether they belong to St. Peter is likely to remain an enduring mystery.
CNN's Vatican analyst John Allen says that like so much concerning religion, the belief that the bones are those of the disciple comes down to faith.
"Like other famous relics, such as the Shroud of Turin or the Belt of Mary, they evoke awe and devotion regardless of their actual provenance," Allen writes in an Op-Ed for CNN. "Faith, as the Bible puts it, lies in 'the evidence of things not seen.'"