At Lourdes, Mary appeared to Bernadette and told her, "I am the Immaculate Conception." When Bernadette reported this to the parish priest, he was astounded because Bernadette was sorely lacking in education and could never have otherwise known about the Immaculate Conception. It had just been declared a dogma not too long before the apparitions.
Lourdes is famous for the miraculous cures of the sick that have occurred there. But even more important is the conversion of hearts that Mary brings about. She always wants to lead us to her son, Jesus.