VATICAN CITY — Pope Francis kicked off the 2025 Holy Year on Tuesday, inaugurating a celebration of the Catholic Church that is expected to draw some 32 million pilgrims to Rome in a test of the pope’s stamina and the ability of the Eternal City to welcome them.

From his wheelchair, Francis knocked a few times and the great Holy Door of St. Peter’s Basilica swung open.

He was wheeled across the threshold as bells tolled across Rome and the choir inside the basilica began Christmas Eve Mass.

In his homily, Francis said the Holy Year is an opportunity to relieve the debt of poor countries and commit to protecting the planet. The aim of the Jubilee, he said, is “to bring hope to the interminable, dreary days of prisoners, to the cold and dismal lodgings of the poor and to all those places desecrated by war and violence.”

The ceremony inaugurated the once-every-25-year tradition of a Jubilee, in which the Catholic faithful make pilgrimages to Rome.

Francis has dedicated the 2025 Jubilee to the theme of hope, and he will underscore that message when he opens a Holy Door on Thursday at Rome’s Rebibbia prison in a bid to give inmates hope for a better future.

Francis has long incorporated prison ministry into his priestly vocation, and has made several visits to Rebibbia and other prisons during his travels.

Security around the Vatican was at its highest levels following the Christmas market attack last week in Germany, the interior ministry said.

Italian authorities were using extra police patrols and camera surveillance around Rome, while pilgrims faced metal detectors and other security checks to access St. Peter’s Square via a reinforced police barricade passage.

Francis, who turned 88 last week, went into the Christmas week and Jubilee launch with a cold that forced him to deliver his weekly Sunday blessing from indoors.

But he appeared in fine form Tuesday night. His health and stamina, already compromised because of his tendency to get bronchitis, are a concern given the rigorous calendar of events during the Holy Year.

One of the highlights will be the canonization of the teenage internet whiz Carlo Acutis, considered the first millennial and digital-era saint, during the Jubilee dedicated to adolescents in April.

This week, Francis also delivers his annual “Urbi et Orbi” (to the city and the world) speech on Christmas Day from the loggia of St. Peter’s Basilica. In addition to the outing at Rebibbia, he will celebrate New Year’s Eve vespers and a New Year’s Day Mass.

The city of Rome entered the Jubilee with some trepidation. It has undergone two years of traffic-clogging public works upgrades of transportation, hospital emergency rooms and other vital services, testing residents’ patience.

But only about a third of the 323 projects have been completed, and the city is already groaning under the weight of overtourism.

Visitors have returned to Italy in droves following COVID-19, and the explosion of short-term vacation rentals has exacerbated a housing crisis.

Some of Rome’s prized monuments have reopened recently, including the Trevi Fountain. The main Jubilee project was finished just in time: A pedestrian piazza linking Castel St. Angelo to the Via della Conciliazione, the main boulevard leading to St. Peter’s Square, was unveiled Monday.

Vatican officials insist that Rome has a tradition of welcoming pilgrims and point to how past Jubilees have left their mark on the Eternal City’s urban and spiritual landscape.

The Sistine Chapel was commissioned by Pope Sixtus IV for the Jubilee of 1475, and the big Vatican garage was built for the 2000 Jubilee under St. John Paul II.

Pope Boniface VII called the first Holy Year in 1300, and in recent times they are generally celebrated every 25 to 50 years.

Pilgrims who participate can obtain “indulgences,” which are related to the forgiveness of sins.

Francis declared a special Jubilee in 2015-2016 dedicated to mercy and the next one is planned for 2033 to commemorate the anniversary of the crucifixion of Christ.

The last regular Jubilee was in 2000, when St. John Paul II ushered in the church’s third millennium.

The one before that, in 1975, was notable because Pope Paul VI was nearly hit by falling plaster when he opened the Holy Door. The door was still behind a fake wall, and Paul had used a ceremonial hammer to bang on it three times to open it.

The fake wall now is removed well in advance.