Hundreds of thousands of young adults were expected to attend the Catholic Church’s World Youth Day (WYD) 2023, which kicked off in Lisbon on Tuesday.
Archbishop Manuel Clemente was to open the six-day event by leading a service on Tuesday evening.
Pope Francis is expected to attend the 37th edition of the event on Wednesday, when the main events get under way.
The event is the largest ever seen by Portugal, with 700,000 registered visitors and assistants.
The organisers are expecting as many as 1.2 million participants.
Prime Minister António Costa said the gathering would be of unimaginable use to the country
WYD 2023 is being held after a study published in February revealed at least 4,815 cases of child sex-abuse linked to the Catholic Church in Portugal.
Other factors, such as 70 million euros (77 million dollars) in public funding, the removal of homeless people from streets and widespread road closures, have met opposition.
Protests were expected to accompany the pope’s visit.
The event was aimed at giving young people the opportunity to meet fellow Catholics from around the world.
A highpoint would be a papal visit to the Fátima Sanctuary, a major site of pilgrimage, the Evening Vigil on Saturday and the Missioning Mass led by Francis on Sunday.
More than 8,000 pilgrims were expected from Germany, according to the German Bishops’ Conference.
German dioceses, church movements and other organisations were also represented, with 17 bishops in attendance.
WYD is held at different locations every two or three years. (dpa/NAN)