Pope Leo XIV drew an estimated 2.5 million people to an open-air Mass in Buenos Aires on Monday, the largest gathering of his pontificate so far. Vast crowds filled one of the Argentine capital's main boulevards for the Mass, held on the first papal visit to Argentina in 39 years.

Local authorities put the turnout at 2.5 million, a figure that would also surpass the crowd that gathered at the same spot for Pope John Paul II in 1982. The pope, 71, is on a 50-event tour of South America less than a month after undergoing lung cancer surgery.

A record crowd on Avenida del Libertador

The Mass was celebrated at the Monumento a los Españoles, an early 20th-century monument at a major intersection in the leafy Palermo neighbourhood of northern Buenos Aires. Argentines stretched for miles down Avenida del Libertador, waving white-and-yellow Vatican flags and pressing against security barriers for a glimpse of the pontiff.

Some in the crowd had camped out overnight to secure a place. Access to the site opened at midnight, on a national holiday declared for the apostolic visit, ahead of the Mass scheduled for 11.30am. The popemobile crossed Avenida del Libertador after 11am, nearly an hour behind schedule, as thick crowds lined the motorcade route.

Leo arrived in Argentina on Sunday after visiting Uruguay, the first leg of a 12-day tour that will take him on to Peru on Wednesday before he returns to Rome on 17 November. On arrival he met President Javier Milei and, in his first speech in Buenos Aires, called on the country's political leaders to safeguard democracy and show a careful use of words.

Family at the centre of the homily

In his homily, the pope praised the Christian family as a source of strength for the Church in Argentina and for the country's society. He told the crowds: "Do not give in to those who dismiss the Christian family as outdated. On the contrary, today more than ever, it remains a pillar amid the many insecurities of our time."

"The family is the place where faith, human virtues, a culture of work, respect for the elderly, the defense of life, and fidelity to one's word are handed on," he said, urging parents to speak naturally to their children about Jesus and to keep the family united in prayer.

The Mass was offered on the feast of the Dedication of the Lateran Basilica, which the pope described as a sign of God's saving presence in his Church. He also told families they should take a leading role in evangelisation, saying the Church in Argentina needed them to support bishops, parish priests, pastoral workers and catechists.

A tour weeks after surgery

The Buenos Aires Mass was the largest event of Leo's 18-month tenure as pope. It came less than a month after he underwent lung cancer surgery, and the schedule is demanding: the three-country tour includes around 50 events.

During his second day in Argentina, the pope also met privately with five survivors of clergy abuse, addressed people with disabilities, and told workers and social movements that the economy must serve the person. He honoured his predecessor, Pope Francis, the first Argentine pope, in the cathedral where Francis once served as archbishop. Francis never made a return trip to Argentina during his 12-year papacy.

What happens next

Leo spends Tuesday in Argentina, travelling to Córdoba before a youth vigil in Buenos Aires in the evening. On Wednesday he flies to Peru, the final country on his South American tour, before returning to Rome on 17 November.

The visit has drawn huge crowds at every stop, and the Buenos Aires Mass sets a new high point for a pontificate that has already taken the first American pope across the continent of his predecessor's birth.