Nearly a million young Catholic believers are expected to attend a nighttime vigil led by Pope Leo XIV on Saturday, which marks the end of a week-long pilgrimage, a key event in the Jubilee holy year.
The "Jubilee of Youth", when the Vatican invites Catholics aged 18 to 35 to the seat of the global Church's power, has seen thousands of young pilgrims from around the world flood Rome this week.
It is taking place just under three months since 69-year-old Leo, the first American pope, took over the papacy.
Large groups of pilgrims have packed the streets of Rome all week, waving the flags of their countries or cities and chanting religious songs.
Excitement has mounted over the course of the week for the new pope's final appearance to the youths on Saturday.
"I feel mainly curiosity, as we don't know him very well yet," Parisian student Alice Berry, 21, told AFP.
"What does he have to say to us? What is his message for young people?"
Various events have been planned for them by the Church throughout the city, including at Circus Maximus, where on Friday approximately 1,000 priests were on hand to take confession.
Some 200 white gazebos lined the hippodrome where chariot races were once held in Ancient Rome, where youth lined up to speak to priests in 10 different languages.
Spanish was one of the main languages heard on the streets of the Italian capital.
The pilgrimage is taking place as economic uncertainty hits young people across the world and as climate change anxiety rises among the under-30s.
Many young pilgrims said they wanted to hear the Vatican's position on climate change, wars and economic inequalities.
Samarei Semos, 29, said she had travelled three days from her native Belize to get to Rome.
"We are still trying to understand his leadership," she said of the new pope, adding she hoped he would have a strong say about "third world countries".
The pilgrimage also comes amid global alarm over starvation in Israel-blockaded Gaza, and more than three years into Moscow's invasion of Ukraine.
The Vatican has praised Catholic youths who travelled to Rome from war-scarred countries like Ukraine or Syria, with Pope Leo repeatedly calling for the youths to "pray for peace".
The voices of the amassed young people "will be heard to the end of the earth," Pope Leo told them earlier this week.
The Vatican has said that more than 146 countries are represented.
The mass that is the climax of the event will take place in Rome's Tor Vergata area in a vast open-air space with a newly built stage for the pope.
It is the same area used 25 years ago for the last youth jubilee under Pope John Paul II.
More than 4,300 volunteers will be working the event to welcome the young pilgrims, along with over 1,000 police, according to organisers.
In an unprecedented move, Leo hosted a mass Tuesday for Catholic social media influencers, signalling the Vatican's openness to supporting the Internet-savvy youth.
Rome authorities have tightened security in the city -- which has seen an unprecedented number of people, with both tourists and pilgrims inundated the city.
