VATICAN CITY — A Vatican archeologist believes he has rediscovered the tomb of St. Paul, buried deep beneath the main altar of the Rome basilica dedicated to the apostle.

The sarcophagus, which lay hidden for centuries, had a hole into which the faithful could stick pieces of cloth to make secondary relics, said Giorgio Filippi, the archeologist and inscriptions expert at the Vatican Museums who carried out the studies.

The tomb lies directly beneath a historic inscription that reads: "Paul Apostle Martyr." The marble sarcophagus was apparently first placed there during reconstruction of the basilica in 390 AD.

"I have no doubt this is the tomb of St. Paul, as revered by Christians in the fourth century," Filippi said as he stood next to the main altar of St. Paul Outside the Walls. He spoke in an interview with Catholic News Service.

Filippi's discovery was the result of more than five years' archeological sleuthing. Surprisingly, the findings have not yet made a huge impression inside the Vatican or in ecclesiastical circles. The Vatican newspaper, for example, has yet to report on the discovery.

The sarcophagus lies several feet below the marble structure of the main altar, embedded in a platform of concrete. Filippi managed to reach the back side of the sarcophagus, but he said opening the tomb would be practically impossible without destroying the altar area.

He added that, in any case, it was not essential to check what's inside the sarcophagus. The important thing is that it was clearly venerated as the tomb of St. Paul, he said.

Tradition holds that St. Paul suffered martyrdom by beheading in the first century, and that his body was buried in a cemetery along the Via Ostiense, where the basilica was built. A first church was erected there in 320 AD, and a larger basilica was constructed in 390; it was remodeled several times over the centuries and almost totally destroyed by fire in 1823.

Pilgrims still come to St. Paul's, but not nearly as many as those who pour daily into St. Peter's Basilica, located some five miles away. On a recent weekday afternoon, no more than 75 people were inside the massive church.

Filippi began his detective work in 1993, when he studied the early Christian inscriptions in the cloister of the basilica and in the monastery nearby. He began asking questions of older monks and caretakers, trying to discover where some of the inscriptions and other artifacts came from.

He soon discovered that by lifting up certain pavement stones in the basilica's floor, a series of underground chambers and tunnels were accessible -- most of them unmapped and forgotten. The excavations yielded a Roman sarcophagus and a wealth of other material.

In the year 2000, Filippi said, pilgrims coming to St. Paul's for the jubilee year asked for the burial place of the Apostle and were disappointed not to see and touch it.

After the jubilee ended, at the request of the basilica's papal administrator and on behalf of the Vatican Museums, Filippi made plans for a systematic study of the area under the altar. In 2002 and 2003, he examined, among other things, three vertical holes leading down to the lid of the sarcophagus.

The holes had been established many centuries earlier so that devotional items could be lowered to the tomb's surface. One reason the tomb ended up so far below the altar was that the altar area had been progressively raised due to changes that occurred through the centuries, Filippi said.

One of these holes -- now closed with mortar -- led inside the sarcophagus, apparently so that pieces of cloth could come into contact with relics of the saint. Filippi said the practice of creating these kinds of secondary relics was popular in the late fourth century, especially after the Emperor Theodosius banned the sale and distribution of corporal relics.

Theoretically, experts today could open the hole to the sarcophagus and stick a small video probe inside. But for now, no such examination is foreseen. Filippi said there's no hurry; as the last 11 years of work has demonstrated, he's happy to take one archeological step at a time.