From April to October, this procession takes place each day at 5.00 pm from the Open-Air Altar on the "Prairie" opposite the Grotto to the Underground Basilica of St. Pius X. It normally last about one hour.
On days when it is raining or in extreme heat, the entire celebration takes place in the Underground Basilica. The procession is conducted in the six usual languages of the Sanctuary.

Each Saturday in July and August at 20.30 in the Church of St. Bernadette (rehearsals for musicians, singers and other participants).The main gates to the Sanctuary are open from 5.30am. to midnight, but access to the domain is available day and night throughout the year by the Grotto.