Lourdes is the most visited pilgrimage shrine in all Christendom. The origins of the pilgrimage to Lourdes began with Bernadette Soubirous, the fourteen year old daughter of devout Christian peasants. Between February 11 and July 16, 1858, Bernadette 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 the apparitions the lady told Bernadette to "go tell the village priest to build a chapel here" and that many people would soon come in procession to the holy grotto. On the day of the 16th apparition, March 25, the lady revealed herself as Mary. During her ecstatic trance in front of the grotto that day, Bernadette suddenly rose from her knees, walked a short distance, and fell to the ground. Fervently she began to dig in the earth until a small puddle of water appeared. Over the next few days the puddle gradually formed into a pool and eventually became the sacred spring for which Lourdes is now so famous.            


From 1864 to 1872 the site was mostly a regional pilgrimage destination attracting approximately 30,000 persons per year. Initially the shrine was not known for its curative power but after 1873, when incidents of healing at the spring began to be reported, the shrine rapidly developed a national and then international reputation for having therapeutic powers. Pilgrims visiting Lourdes for its healing powers bathe in pools filled with cold water piped from Bernadette's spring. Reports of miracles are thoroughly examined and evidence seems to indicate that there are indeed many cases of verifiable healings at the grotto.


The increasing number of pilgrims eventually overcrowded the original basilica, built above the grotto in 1876, and in 1958 an immense concrete church, seating 20,000, was built. The stream of pilgrims to Lourdes is characterized by strong seasonality. The season lasts from April through October, with the main pilgrimage day being August 15, the Marian Feast of Assumption. Four to six million pilgrims visit the shrine each year, and a study done in 1978 showed the pilgrims coming from 111 countries with females accounting for 69% of the pilgrims. It is estimated that more than 200 million pilgrims have come to Lourdes since 1860. According to theories regarding the powers at sacred sites, this large number of devout pilgrims has contributed to and thereby amplified the field of holiness that surrounds the shrine of Lourdes. This field then attracts more pilgrims, who in turn contribute to the further empowerment of the field.