Pope Leo XIV, the first U.S. pontiff, made his debut tour of St. Peter’s Square on Sunday in a popemobile, greeting tens of thousands of pilgrims and well-wishers ahead of his inauguration mass.

Chicago-born Robert Francis Prevost, who became the leader of the world’s 1.4 billion Catholics on 8 May, stood in the white vehicle as it drove through cheering crowds, smiling, waving and making the sign of the cross.

U.S. Vice President JD Vance is among the hundreds of dignitaries expected to attend the inauguration mass, which is scheduled to begin at 10 a.m. local time (0800 GMT).

Leo is set to preside over a ceremony steeped in tradition, where he will receive his special papal ring and deliver a homily expected to outline the tone and priorities of his papacy.

The 69-year-old spent two decades as a missionary in Peru and remains relatively unknown to many Catholics. Over the past week, however, he has offered a glimpse of his leadership approach, meeting with journalists, clergy and diplomats.

In those meetings, he has repeatedly called for peace in a world full of conflict and voiced support for social justice. He has also emphasized traditional Catholic values, including the importance of family and the rights of the unborn.

Inacia Lisboa, 71, originally from Cape Verde and now living in Rome, said she arrived early to get a good spot to see the new pope.

Asked what she wanted to hear from him, she told AFP: “The first thing is that he prays for us all, for peace in the world — we need it so much.”

Global leaders attend

Leo’s elevation has generated significant excitement in the United States, which is being represented at the ceremony by Vance — who converted to Catholicism in 2019 — and Secretary of State Marco Rubio.

Before becoming pope, Leo used his personal X account to repost criticism of former President Donald Trump’s administration over its migration policies, as well as to criticize Vance. The account is no longer publicly accessible.

Vance was the last world leader to meet with Pope Francis before his death on April 21. The Argentine pontiff served for 12 years.

Other world leaders expected at the ceremony include Ukrainian President Volodymyr Zelensky, German Chancellor Friedrich Merz, Peruvian President Dina Boluarte, European Commission President Ursula von der Leyen, Canadian Prime Minister Mark Carney, Israeli President Isaac Herzog, Colombian President Gustavo Petro, and several European royals.

Italian security forces have deployed thousands of officers, including rooftop snipers and anti-drone teams, to ensure safety during the event.

Ceremonial rites

Leo XIV was elected the 267th pope on May 8 following a conclave of cardinals that lasted less than 24 hours.

He succeeds Pope Francis, a charismatic but at times unpredictable leader, and inherits a Church still grappling with the fallout of clerical sexual abuse scandals and challenges in adapting to the modern world.

Though popes have not been crowned during inauguration masses since Paul VI in 1963, the ceremony remains a grand occasion rich in Catholic tradition.

The day began with a visit to the tomb of Saint Peter — believed to be the first pope — located beneath the altar of St. Peter’s Basilica.

Leo is set to receive the papal emblems: the pallium, a cloth band worn over his chasuble, and the Fisherman’s Ring, a new version cast for each pontiff. The ring will be worn throughout his papacy and destroyed after his death.

The new pope will process with clergy and cardinals into St. Peter’s Square, where the mass will be broadcast on large screens for the gathered crowds.

Following the ceremony, Leo is expected to greet attending heads of state. It remains unclear whether any will be granted private audiences.