The Shroud of Turin, the linen some Christians believe to be the burial cloth of Jesus Christ, is to go on display in a rare exposition that is expected to attract millions of visitors.
The shroud, that measures 14 feet, bears an image some worshippers say is that of Christ.
The length of the cloth is marked by what some believe are drops of blood from wounds in the wrists and feet.
Carbon dating tests in 1988 placed the cloth in the 12th or 13th centuries, causing a sensation -- and prompting some hard-core believers to challenge the scientific results.
Even the Catholic Church doesn't claim the Shroud's authenticity, but says it should be a powerful reminder of Christ's passion.
Some visitors who got a chance to see the Shroud at a preview event on Saturday described being touched by the shroud and its history.
The Shroud, which goes on display today, was last seen in 2010.
Authorities expect the Shroud to attract millions of pilgrims, including the Pope himself who will pay a visit to the Cathedral in June.