During his trip to France, Pope Leo XIV venerated the relic of Christ's Crown of Thorns. This is a sensitive topic in France, dating back to the 13th century: “There are no references to this crown in the accounts of the first relic seekers in the Holy Land. In the 4th century, Saint Helena, the mother of Constantine, went to the Holy Land and found the Cross, the INRI inscription, and other relics of the Passion, but neither Saint Helena's chronicles nor those of other pilgrims mention the Crown of Thorns. The first to do so was Saint Paulinus of Nola in the 5th century,” he explained.

Sierra recounted that it was in the 13th century when Baldwin II of Constantinople pawned the relic to Venetian merchants in exchange for 13,000 gold coins. “Since the Venetians could not reclaim it, they sold it to the King of France, Louis IX, who paid the equivalent of half of France's GDP at that time for the crown.”

The monarch ordered the construction of a chapel a few meters from Notre Dame to house the relic, which Leo XIV has now been able to see: “It is an object that almost disappeared in the 2019 Paris fire. Until 2024 it was in the Louvre Museum, where it was restored, but no investigation was carried out because its state of conservation is very delicate, and we have lost an opportunity to know if it is or is not something from the time of Jesus,” lamented Javier Sierra.