Hundreds of thousands of people packed St. Peter's Square on Sunday for the elevation to  sainthood of two popes together for the first time, John XXIII and John Paul II.

The two popes were towering 20th century leaders of the Catholic Church.

The canonization ceremony and mass following it involved four popes, the two being elevated to sainthood and Pope Francis who led a mass assisted by Pope Emeritus Benedict.

It began with a litany of the saints and a procession of 150 cardinals with some 1,000 bishops, 6,000 priests and 24 heads of State, or country leaders, present.

The Catholic Church's two newest saints were "popes of the 20th century" and "were not afraid to look upon the wounds of Christ," said Pope Francis in his homily.

"They lived through the tragic events of that century, but they were not overwhelmed by them," Francis said. "For them, God was more powerful; faith was more powerful - faith in Jesus Christ the Redeemer of man and the Lord of history."

During the mass in the leadup to the Eucharist ceremony involving holy communion, the two new saints were named in prayer.

All through the night until the morning people from every part of the world celebrated with  singing, prayer vigils and dancing.

Police opened the main street leading to the Vatican about four hours before the ceremony with many families in line.

The two men lifted to sainthood on Sunday were born Angelo Giuseppe Roncalli, an Italian who became Pope John XXIII and Karol Jozef Wojtyla who became the first Polish Pope, John Paul II.

SECOND VATICAN COUNCIL

John XXIII was pope from 1958 to 1963 and the Second Vatican Council changed the Catholic Church for ever in his short reign. John Paul II was pontiff for almost 27 years and influenced world affairs.

Thousands of Poles, some of whom made a marathon run from their homeland to Rome, waving Polish flags were present at the Vatican for the sainthood ceremony.

Many people in Poland see John Paul as an inspiration for the end of Soviet-imposed Communist rule of their country following on the Nazi occupation.

Both of the sainted popes were highly regarded by global Jews with a big Jewish delegation at Sunday's ceremonies.

The Simon Wiesenthal Center, a global Jewish human rights organization, said earlier in April it was joining with Roman Catholics around the world in acknowledging the remarkable contribution of the two popes.

"Jews will always remember Pope John XXIII as the animating force behind the Vatican II Council that changed the way Catholics looked at other faiths, especially Judaism.

John Paul was the first pope to officially visit a synagogue in 1986.

Following the canonization mass, Pope Fancis said, "My greeting goes to all the pilgrims - here in St. Peter's Square, in adjacent streets and in other locations in Rome.2

He also thanked "those who are united to us through radio and television; and thank you to the media directors and personnel, who have given many people the possibility to participate. For the sick and the aged, to whom the new saints were particularly close, I add a special greeting."