VATICAN CITY (Reuters) - Pope John Paul led the world's nearly one billion Roman Catholics in Good Friday ceremonies to commemorate the most solemn day in the Christian calendar, the crucifixion and death of Jesus Christ. The day's events began with the Pope entering a wooden confessional in Christendom's biggest church, St Peter's Basilica, to sit and hear the private confessions of 15 pilgrims picked at random. Confession is considered an integral part of Roman Catholic faith, in which the faithful ask for forgiveness for their sins. The Pontiff, who turns 78 next month, heard confessions of 10 Italians, including scouts, soldiers, students, a nurse and a pregnant women. A Polish woman, a young woman from Burkino Faso, a Spanish couple and two American students were also shepherded towards the narrow wooden confessional within the vast basilica to give their confession to the Pope. The Pope, in the 20th year of his papacy, will preside at a "Passion of the Lord" service in St Peter's, in which the congregation remember the last hours of Christ's life before his crucifixion. The Pope will later lead a traditional candlelit Via Crucis (Way of the Cross) procession around Rome's ancient Colosseum, where thousands of Christians were put to death or fed to lions in the time of the Roman Empire. The four days of ceremonies culminating on Easter Sunday will be a test of the frail Pope's stamina. On Holy Saturday night, the Pope will preside at an Easter vigil mass in St Peter's Basilica. The culminating event of the Pope's four days of ceremonies is on Easter Sunday, when he celebrates a mass in St Peter's Square to commemorate Christ's resurrection from the dead. The Pope will deliver his twice-yearly "Urbi et Orbi" (to the city and the world) message and blessing at noon on Sunday. In the past, hundreds of thousands of people have packed St Peter's Square and the surrounding area for the Easter service, which is transmitted live around the world.