Lourdes is where Bernadette Soubouris had the visions of "The Lady", which turned out to be Mother Mary.
The Church approved Lourdes, the place where the visions happened, as a suitable place for devotions. Hence, pilgrimages to Lourdes to pray to Our Lady of Lourdes began.
Pope John Paul II attributed his survival of the assassination attempt on himself in Rome to the protection of Our Lady of Lourdes. He placed the bullet in the crown on the statue.