ROME — Walking in the footsteps of both Popes John Paul II and Benedict XVI, Pope Francis will travel to the Italian city of Turin on June 21 to venerate its famous shroud, traditionally regarded as the burial cloth of Jesus Christ.

The shroud will be placed on display in the Turin cathedral from April 19 to June 24, marking one of the rare occasions when the revered but controversial cloth will be available for public viewing.

On the same trip, Francis also will pay tribute to Italian St. John Bosco, founder of the Salesian religious order, on the bicentennial of his birth. “Don Bosco,” as he was known, dedicated his life to helping and educating street children, juvenile delinquents, and other disadvantaged youth.

The Shroud of Turin is a piece of linen cloth that, according to Catholic tradition, was used to wrap the body of Christ after his death on the Cross. It contains a full-length photo-negative image of a man, front and back, bearing signs of wounds that correspond to the Biblical accounts of Jesus’ crucifixion.

To date there’s no scientific consensus on how the image was created. Skeptics regard it as a later forgery, while devotees believe it was burned into the cloth at the time of Christ’s resurrection.

All three recent popes have been careful not to pronounce definitively on the authenticity of the shroud, generally referring to it as an “icon” that inspires genuine faith regardless of its historical origins.

“The pope comes as a pilgrim of faith and of love,” said Archbishop Cesare Nosiglia of Turin, papal custodian of the Shroud, during a Vatican news conference Wednesday to announce the pope’s trip next June.

“Like his predecessors did, Pope Francis confirms the devotion to the shroud that millions of pilgrims recognize as a sign of the mystery of the passion and death of the Lord,” Nosiglia said.

In 1978, a detailed examination carried out by a team of American scientists found no evidence of how the image was produced.

A radiocarbon dating test performed in 1988 over small samples of the icon by three laboratories, at the universities of Oxford and Arizona, and the Swiss Federal Institute of Technology, concurred that the samples they tested dated from the Middle Ages, between 1260 and 1390.

Other scientists, however, believe those results could be off by centuries, pointing to the possibility of bacterial contamination of the cloth. They note, for instance, that burial shrouds for Egyptian pharaohs sometimes test to centuries later than their known age for precisely that reason.

Despite the controversies, Pope Benedict XVI visited the shroud during its last public exhibition in 2010, and St. John Paul II did so three times: in 1998, in 1980, and in 1978, months before the conclave that elected him pope.

During the first days of his pontificate, Francis referred to the disfigured face depicted in the Holy Shroud as “all those faces of men and women marred by a life which does not respect their dignity, by war and violence which afflict the weakest …”

The message was made public on March 30, 2013, hours before footage of the icon was shown on TV for the first time in four decades.

During the press conference, organizers of the exhibition announced that more than 1 million people from all over the world are expected in Turin to venerate the icon.

The visit to the display in the city’s cathedral will be free, but to regulate the massive flow of visitors, mandatory reservations should be made through the official website.