Nuns buy portraits of late Pope John Paul II in a shop near St. Peter's Square at the Vatican on Friday. (AP)

Two popes have never been canonized in the same ceremony until John XXIII and John Paul II. But did you know that the first 35 popes were all saints, a streak that ended with the controversial Pope Liberius, who died in 366?

We asked Matthew Bunson, a papal expert who writes for Our Sunday Visitor and penned "The Encyclopedia of Saints," and Post correspondent Anthony Faiola to help us list a few more canonization facts.

— The crowd expected in Rome on Sunday will be the largest ever for a canonization; the second-largest crowds attended the canonizations of Padre Pio and Josemaría Escrivá, the founder of Opus Dei, both in 2002, with crowds estimated at 300,000 to 350,000.

- At least 1,700 buses, 58 charter flights and 5 train-loads of pilgrims came in to Rome just from Poland, the birthplace of John Paul II.

— Nearly 15,000 police, clerics, volunteers and other support staff were expected to fan out across the Holy See as well as the city of Rome, where massive screens were set up in ancient squares and picturesque parks.

— John Paul II is the fastest person declared a saint in modern times; St. Anthony of Padua was canonized in 1232, less than a year after his death; St. Francis of Assisi was canonized less than two years after his death.

— John Paul II proclaimed 482 saints, more than in the previous 600 years combined.

— The first beatification of two popes was held in 2000, with the beatifications of Pius IX and John XXIII — by Pope John Paul II.

— The first officially canonized saint was Ulrich of Augsburg, canonized in 993 by Pope John XV.

— The Roman Martyrology, the official listing of saints, boasts 47 saints named Felix, including three popes.

— Eighty popes have been canonized, including John XXIII and John Paul II, out of a total of 265 popes.

— Three popes of the 20th century are now saints — Pius X, John XXIII and John Paul II; three others have causes open for their possible canonization.