Pope Leo XIV is set to begin a four-day visit to France on Friday, with more than half a million Catholic faithful expected to attend a major Mass in central Paris on Saturday.
An altar has been erected at the Place de la Concorde, while police have secured large sections of the surrounding area, including the Champs-Élysées, ahead of the celebration.
Organisers expect approximately 600,000 people to gather along the avenue towards the Arc de Triomphe and beyond, as the Pope's visit draws large crowds across the country.
French President Emmanuel Macron will welcome the Pope at Orly Airport before holding talks with him at the Élysée Palace on geopolitical issues and artificial intelligence.
The two leaders are also scheduled to deliver a speech in Metz.
Macron will not attend the Pope's Masses, in line with France's principle of separation between religion and the state.
His wife, Brigitte Macron, and Prime Minister Sébastien Lecornu are expected at the Paris celebration.
Pope Leo will also meet young people at the Stade de France, visit Notre-Dame Cathedral and travel to Lourdes, where 150,000 people have registered for Sunday Mass.
The pontiff's itinerary includes a meeting with migrants in Paris and survivors of sexual abuse by Catholic clergy in Lourdes.
On Monday, he will visit Metz to honour Robert Schuman, one of the founding figures of the European Union.
The visit comes amid signs of renewed interest in religious life in France, despite decades of declining church attendance and secularisation.
