Vatican City: Pope Francis on Sunday proclaimed John Paul II and John XXIII as saints of the Catholic Church to applause from the crowd of pilgrims in St Peter's Square.
"We declare and define as saints the blessed John XXIII and John Paul II," Francis said in a Latin prayer, as pilgrims and foreign dignitaries chanted back "Amen!"
Pope Francis opened a mass attended by hundreds of thousands of pilgrims to confer sainthood on two influential pontiffs who helped shape 20th century history - John Paul II and John XXIII.
Many faithful waved red-and-white flags from John Paul II's homeland Poland and thousands spent the night camped out in and around the Vatican in a Catholic festival atmosphere of singing, dancing and praying.
Thousands also followed the ceremony on giant screens in some of the most picturesque spots of Rome, witnessing an event seen by Vatican experts as a way of uniting conservative and reformist wings of Catholicism.
Francis is co-celebrating the mass with his predecessor Benedict XVI and hundreds of bishops and cardinals - the first time that two living popes say mass together.
Benedict, who now lives in a former monastery in the Vatican, wore his white papal cassock and mitre and waved as he arrived for a rare public appearance.
It is also the first time that two Catholic Church leaders are being sainted on the same day and many commentators defined the event as "four-pope day".
"We are followers of all four popes who have all been close to the people. This is an historic day but one that you really feel inside," said Luisa Tomolo, a member of an Italian religious movement.
John Paul II helped topple Communism in Eastern Europe and John XXIII is best remembered for launching a process of reform of the Catholic Church in the 1960s.
Former German chancellor Helmut Kohl paid tribute to John Paul II in an editorial for Il Messaggero as the man who helped topple Communism in Eastern Europe.
"He played a decisive role in making the fall of the Berlin Wall possible," Kohl said, adding that the Polish pope had been "a fearless fighter for freedom".
The Vatican's official Osservatore Romano daily ran a headline reading simply "Saints" next to pictures of the two popes and a banner held up by a pilgrim read: "Two pope saints in heaven, two in St Peter's Square".
Francis has reached levels of popularity not seen since the glory days of John Paul II but Vatican experts say he is more comparable to John XXIII - a down-to-earth unifying figure with the style of a parish priest.
By sainting them together, Francis "is speaking not just to the outside world but to rival camps within the Catholic fold who see John XXIII and John Paul II as their heroes", said US-based Vatican expert John Allen.
The ceremony was relayed in different languages on giant screens around the Eternal City including at Fiumicino airport, the Colosseum and Piazza Navona.
It was also being shown in 3D at hundreds of cinemas across the world from Francis's native Argentina to Lebanon and was live tweeted by the Vatican's vicariate of Rome under the hashtag #2popesaints.
