Lourdes, France - Catholics began marking Saturday 150 years since a young shepherdess saw visions of the Virgin Mary, with thousands of pilgrims expected at her shrine at Lourdes over the next year, including Pope Benedict XVI.
The celebrations, coinciding with the feast of the Immaculate Conception, a key date in the Catholic calendar, began with a mass celebrated by Indian Cardinal Ivan Dias before some 20,000 faithful, including 400 priests, bishops and other cardinals.
It was followed by the solemn opening of the gates leading to the pilgrim trail to the holy places where Bernadette Soubirous lived and experienced 18 apparitions of the mother of Jesus Christ between February and July 1858.
These include the church where she was baptised, the former prison cell where her poverty-stricken family lived, the grotto where she had her visions and a chapel.
Preceded by a wave of brightly-coloured banners of the local dioceses, the pilgrims marched in procession to the grotto and the chapel.
On Friday evening they had visited the other two spots in a torchlight parade.
"It is a way of concentrating on the essential details," Bishop of Lourdes Jacques Perrier said.
Perrier said that while there had been no new building to mark the 150th anniversary, unlike the basilica constructed at the time of the centenary, five coloured mosaics of gospel scene would be unveiled on the grey church.
The pope is expected to visit the site at some point, "certainly in autumn" during the celebrations, Perrier said.
The town of Lourdes in southwestern France is one of the main pilgrimage sites in the cult of Mary maintained by the Catholic Church, attracting millions of Christians from around the world.
The series of visions experienced by Bernadette Soubirous included confirmation of the dogma of the Immaculate Conception, proclaimed four years later by Pope Pius IX, which declares that Mary was "without sin" when Jesus Christ was conceived.
The Vatican said earlier this week that Pope Benedict XVI would grant indulgences for a limited time to pilgrims who visit Lourdes for the 150th anniversary.
In the Catholic Church, indulgences are remittances of suffering for sins. In order to go to heaven, it is believed one must 'repair' the harm committed on earth before death.
In Rome, the pope prayed for the Lourdes pilgrims who were "honouring the Virgin Mary in this jubilee year of the 150th anniversary of the appearance of Our Lady to Saint Bernadette."
He was speaking on his annual visit to a statue of Mary in central Rome to mark the feast of the Immaculate Conception.
He laid a large bouquet of white roses at the foot of the statue and knelt briefly before delivering a homily.
"I ask the Virgin Mary to watch over the inhabitants ... of Lourdes and I grant all of them, as well as the pilgrims attending the ceremonies, an affectionate apostolic blessing," he said.