It is not unusual to see pilgrims crawling on their hands and knees up the steps and across the esplanade that leads to the shrine of Our Lady of Fatima where Pope Benedict XVI will visit this week.
After making a holy vow of penitence, some walk for miles and then crawl past the souvenir shops, chapels, hospitals and hostels for sick pilgrims that surround the main basilica in the town that has become the bastion of Portuguese Catholicism.
Fatima is big business, spiritually and commercially.
About four million people go to the town each year to see the place where three shepherd children -- Lucia Santos, 10, Jacinta and Francisco Marto, aged nine and seven -- say they saw a vision of the Virgin Mary on May 13, 1917 and then again on four other occasions.
They also say they saw her on August 19 of that year in the neighbouring village of Valinhos.
Since then it has been one of the Church's most important pilgrimages. Pope Paul VI went there in 1967 and Pope John Paul II in 1982, 1991 and 2000. John Paul said the Fatima angel saved him from an assassin's bullet in May 1981.
Benedict will spend two days at the shrine town where between 300,000 and half a million people are expected to join him on Thursday morning for a special mass in the esplanade to mark the 10th anniversary of the beatification of Francisco and Jacinta.
The pope arrives in Fatima on Wednesday, the second day of a four day stay in Portugal, and his first duty will be to pray in front of the statue of Our Lady of the Rosary at the Chapel of Apparitions built on the site where the children said they were told holy secrets by the Virgin Mary.
After the first visions, thousands quickly started to join the children at monthly gatherings. But the church was at first sceptical and it was only in 1930 that the Vatican declared the apparitions as being "worthy of belief".
Since then, hundreds of thousands of pilgrims have gathered at the basilica each May 13, overruning the central Portuguese town which normally has a population of about 15,000.
Fatima is today "the epicentre and the central pillar of popular Portuguese Catholicism and it is very strongly linked to the cult of the Virgin," sociologist Steffen Dix told AFP.
Some Catholics call Fatima the "Altar of the World" and the pilgrims who walk hundreds of miles to the town or crawl across the esplanade are a mark of the religious devotion that it inspires.
Since 1952, the bodies of Jacinto and Marta Santos have been in the main basilica. Their cousin Lucia died in 2005 at the age of 97, and is also laid to rest in the shrine.
In 2007, the Church of the Most Holy Trinity was completed at the complex, and at 12,300 square metres (132,000 square feet) it is one of the largest Christian churches in the world.
Lucia said that the Virgin Mary had told the children three secrets. Two were revealed at the start of the 1940s, one described hell, and the second a terrible conflict which some say was World War I and World II.
Fatima was used a national symbol by the right-wing dictatorship which ruled Portugal from the 1930s until 1974.
"Today it has lost all ideological connotation and nobody uses it for any anti-communist reference," said Dix, who has written 10 books on religion in Portugal.
The third secret was revealed in May 2000 during John Paul II's final visit. According to the Church, it predicted the attack that the pope was a target of in Rome 1981, strengthening the prophetic nature of Fatima.
Speculation over the secret has been the subject of books and hundreds of web sites and even inspired a 1981 hijacking of an Aer Lingus flight between Dublin and London by an Australian man who wanted the Vatican to reveal it.
Today the bullet that hit John Paul II is part of the crown on the statue of the Virgin Mary in the basilica.
Copyright 2010 AFP Global Edition
