Fulgens Corona §33

³³ But where - as is the case in almost all dioceses, there exists a church in which the Virgin Mother of God is venerate with more intense devotion, thither on stated days let pilgrims flock together in great numbers and publicly and in the open give glorious expression to their common Faith and their common love toward the Virgin Most Holy. We have no doubt that this will be done in an especial manner at the Grotto of Lourdes, where there is such ardent devotion to the Blessed Virgin Mary conceived without stain of sin.