About 2.5 million people attended an outdoor Mass celebrated by Pope Leo XIV on Monday in Buenos Aires’s Palermo district, MercoPress, the Buenos Aires Times and ABC News Australia reported, citing local authorities or the Vatican^1,2,3.

Outlets described it as the first papal Mass in Argentina since John Paul II’s visit in 1987 and among the largest crowds of Leo’s pontificate^1,2,3.

The 71-year-old pope had surgery for lung cancer about three weeks earlier, the Buenos Aires Times and the BBC said^2,4.

Worshippers lined Avenida del Libertador and followed the liturgy on dozens of giant screens, MercoPress and the Buenos Aires Times reported^1,2.

Leo’s homily treated the family as a source of social values and recalled Pope Francis, MercoPress and the Buenos Aires Times said^1,2.

The Buenos Aires Times said he later met five people who described abuse by clergy or in church-run institutions and, according to a Holy See statement, pledged stronger safeguarding; MercoPress and ABC did not include that meeting^2,1,3.

ABC News Australia said the Mass came after Leo appeared to criticize President Javier Milei’s economic policies; the Buenos Aires Times account of the Mass itself did not frame the homily as a rebuke of Milei^3,2.

The Mass was the second stop on a 12-day Latin America tour, the BBC said⁴.