Pope Francis is in Poland to preside at a gathering of more than a million Catholic youth from around the world, sometimes called the "Catholic Woodstock".
However, the usually joyous event is being held in the aftermath the murder of a priest in a church in Normandy, France. The killing of 85-year-old Father Jacques Hamel, forced to his knees by Islamist militants who then slit his throat, has added to security fears surrounding the Pope's visit for World Youth Day.
Pope Francis waves as he is welcomed by Polish President Andrzej Duda and his wife Agata Kornhauser-Duda at Balice airport near KrakowDavid W Cerny/ReutersPeople in traditional outfits wait for the arrival of Pope Francis at John Paul II International airport in Krakow-BaliceJoe Klamar/AFPPope Francis is greeted as he is driven from Balice military airport into KrakowJoe Klamar/AFPPope Francis is welcomed by the faithful as he travels to Wawel Royal Castle in KrakowKacper Pempel/Reuters
Thousands of young Catholics from around the world are gathered in Krakow for the festival. Over 350,000 people from 187 countries have registered online but organisers expect up to 1.5 million people to attend the main events, which include a night vigil with the pope on Saturday (30 July) and an open-air mass celebrated by the pontiff on Sunday.
Pilgrims dance during World Youth Day in KrakowAgencja Gazeta/Michal Lepecki/ReutersPilgrims covered in rain coats play on World Youth Day at the Main Square in KrakowAgencja Gazeta/Mateusz Skwarczek/ReutersPilgrims wearing raincoats pray before the opening ceremony of World Youth Day in KrakowDavid W Cerny/ReutersDespite the heavy rain, pilgrims gather on the Blonia Meadows in Krakow, to celebrate the Opening MassWojtek Radwanski/AFPA pilgrim waits for the opening ceremony of World Youth Day in KrakowDavid W Cerny/ReutersPilgrims sing songs at the main square during World Youth Day in KrakowDavid W Cerny/ReutersA pilgrim prays during the World Youth Day Opening MassJoe Klamar/AFPA priest gives a holy communion to a pilgrim during the Opening Mass in KrakowJoe Klamar/AFPPilgrims from Brazil walk the streets of Krakow after the Opening MassBartosz Siedlik/AFPPilgrims pray during the Opening Mass for World Youth DayJanek Skarzynski/AFPPilgrims from all over the world celebrate after the Opening Mass of World Youth DayJanek Skarzynski/AFPYoung people and a monk play football in front of the main railway station in KrakowJanek Skarzynski/AFPYoung Catholics and a nun from France dance on the market square in KrakowJanek Skarzynski/AFPYoung people from around the world gather at the market square in KrakowJanek Skarzynski/AFP
World Youth Day was established in 1985 by Polish-born Pope John Paul II, whom Francis declared a saint in 2014, and aims to inspire young people to follow Christian values of peace and love in life. The gatherings are held every two or three years. The first meeting was held in Rome in 1986, attended by John Paul II and some 30,000 participants. The largest World Youth Day gathering was in the Philippines in 1995, when an estimated five million people attended a Mass celebrated by John Paul II.
A woman carries a Pope Francis puppet near Cracovia Stadium in KrakowAgencja Gazeta/Jakub Porzycki/ReutersA poster with Pope Francis is seen near Cracovia Stadium in KrakowAgencja Gazeta/Jakub Porzycki/ReutersA policeman stands guard during the Opening Mass in KrakowJoe Klamar/AFPA pilgrim poses next to a picture of Pope Francis at the main square during World Youth Day in KrakowDavid W Cerny/ReutersA pilgrim watches a mass on a large screen in KrakowJoe Klamar/AFPA priest listens to a confession on the first day of the World Youth Days in KrakowJoe Klamar/AFPA view of the altar during the Opening Mass in KrakowJanek Skarzynski/AFP
Security was already tight after a string of violent attacks in France and Germany. Polish officials say they have deployed tens of thousands of security officials to cover the event. Francis is expected to use the event to pay tribute to the murdered priest, who some say should be declared a martyr because of the way he was killed for his faith.
Pope Francis said the murder was particularly "barbarous" because it happened during the central rite of Christian worship as the priest was saying morning Mass. He spoke to reporters on the papal plane en route from Rome to Poland. Asked about the slaying of the priest, Francis replied: "It's war, we don't have to be afraid to say this." He clarified that when he speaks of war, he is speaking of "a war of interests, for money, resources. ... I am not speaking of a war of religions. Religions don't want war. The others want war."