(Reuters) - Pope Benedict visits the shrine at Lourdes in southwestern France, in the foothills of the Pyrenees, from Saturday to Monday to commemorate the 150th anniversary of when the Virgin Mary is said to have appeared to a peasant girl Bernadette Soubirous in 1858.
Here are some key facts about Lourdes:
* Between February 11 and July 16, 1858, a teenage French peasant girl named Bernadette Soubirous said she saw apparitions of a white-robed lady 18 times in a small grotto called Massabiele along the banks of the river Gave de Pau in Lourdes.
* On the day of the 16th apparition, March 25, the lady said: “I am the Immaculate Conception,” i.e. Mary, the mother of Jesus. Bernadette dug in the earth until a small puddle of water appeared which gradually formed into a pool and eventually became the sacred spring whose water Lourdes pilgrims believe can heal illnesses.
* The first healings at Lourdes were reported in 1862. The reports and the opening of a railway link in 1866 helped boost pilgrimages to the site. Initially only frequented by French, Lourdes received its first foreign pilgrimage group -- from Belgium -- in 1874. Pilgrims now come from around the world.
* Pilgrims bathe in pools filled with cold water piped from the spring. A total of 67 miraculous healing have been recognized there. A medical commission examines reports of miracles thoroughly and most are rejected as not true cases of scientifically inexplicable healing. The last miracle was recognized in 2005.
* The season lasts from April through October, with the main pilgrimage day being August 15, the Feast of the Assumption. It is estimated that more than 200 million pilgrims have come to Lourdes since 1860.
* About six million pilgrims visit Lourdes annually and the city has second largest number of hotels in France after Paris.
* Lourdes created its Medical Bureau in 1905 to examine claims of miraculous healing and certify those cases judged to be inexplicable according to current scientific knowledge. Cases are reviewed first by a doctor at Lourdes and, if considered serious, by a 20-member International Medical Committee of Lourdes. A two-thirds vote is needed to certify a miracle.
* The progress of medical science has meant that fewer and fewer healings cannot be explained. From 24 in the first decade after 1900, the number slowed to about one per decade at the end of the century. The last case, the 1951 cure of Italian Anna Santaniello from a heart valve disease, was certified in 2005.
* About 40 people declare themselves cured because of Lourdes every year.
* Bishop Jacques Perrier of Lourdes and Tarbes has said the strict conditions for miracles leave no room for the Church to validate unusual healings linked to Lourdes. He has proposed new categories below the miracle level, including exceptional and unexpected healings, to better reflect the spiritual experience these pilgrims have had.
POPES AND LOURDES
* Pope John Paul visited Lourdes twice, first in August 1983 and then in August 2004 on his last voyage abroad before dying in April 2005.
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