Amid security worries, millions of pilgrims are expected to descend on Rome for a Jubilee Year of major Catholic celebrations throughout 2025. Here are the highlights.

According to the Vatican, the tradition began in 1300 when Pope Boniface VII announced the first Jubilee. Later, Jubilees came to be celebrated every 25 years.

Pope Francis opened the "Holy Door" of St Peter's Basilica on Christmas Eve on Tuesday, launching the Jubilee year of Catholic celebrations set to draw more than 30 million pilgrims to Rome. Pope Francis then presided over the Christmas Eve mass in St Peter's,