Pope Francis prayed before the mysterious Turin Shroud, believed by some to be Jesus's burial cloth, but skirted the issue of its authenticity, saying it should remind people of all suffering and persecution.
On the first day of his visit to the northern industrial city of Turin, he defended migrants flocking to Europe to escape war and injustice, saying it "makes one cry" to see them mistreated.
He also spoke of the city's 19th-century reputation as a centre of devil worship and anti-clericalism, saying today's young people faced new snares of high unemployment, drugs and unbridled consumerism.
Pope Francis was the latest of many popes to view the shroud, which is usually kept locked out of sight and is on display for only the third time in 17 years. More than a million people have seen it in two months.
After praying for several minutes before the cloth that has baffled scientists for decades, he touched its glass case and moved on to say Mass for 60,000 people. There he said the Shroud should spur people to reflect not only on Jesus but also on "the face of every suffering and unjustly persecuted person".
The Catholic Church has not taken an official position on the cloth bearing an image, reversed like a negative, of a man with the wounds of a crucifixion.
Sceptics say it is a masterful medieval forgery and carbon dating tests in 1988 dated it between 1260 and 1390, but some have challenged the accuracy of those tests.
The Pope began the day with an outdoor rally on the theme of workers rights and immigration.
"Immigration increases competition but migrants should not be blamed because they are the victims of injustice, of this throw-away economy, of wars," he said.
Departing from his prepared text, he added: "It makes one cry to see the spectacle of these days in which human beings have been treated like merchandise."