Visit the sacred sites, including the Grotto where St Bernadette saw Mary. Attend mass dozens on offer in almost every language in the world somewhere in or around the holy sites. Visit one of the many Bernadette attractions several museums, her former home, etc. and best of all: watch the astonishing numbers of pilgrims from all over the world. The Underground Basilica of St. Pius X, a church constructed entirely underground, is especially interesting architecturally.
Especially interesting is the International Mass, held in six languages English, French, Italian, Spanish, German, and Dutch simultaneously in the Underground Basilica of St. Pius X Sunday mornings. Arrive early to get a seat. One wonderful experience is to arrive about 1 1/2 hours early to be part of the choir open to anyone who arrives early to rehearse. You get to sing with people of all 6 languages and have a excellent view of the Mass.
Don't miss the nightly candlelight procession buy your candle beforehand from one of the souvenir shops in front of the Basilica and around the main square, with singing, prayer and a rosary said in many languages alternating half-decades in English, French, Italian, etc.. The procession of the sick to the Underground Basilica each afternoon is particularly moving, as well. Other religious activities available include confession available in French, English, Spanish, Italian, German, Dutch, adoration, stations of the cross in the underground basilica, candle lighting near the Grotto, and rosary in front of the Grotto each afternoon in French and at other times/places in other languages.
If you have a car, spend a day in the wonderful Pyrenees. Roadtrips to Pont d'Espagne, Gavarnie or de Col de Tourmalet offer breathtaking mountain scenery and lots of opportunities for hiking. There is a historic chateau on a hill visible from the town, as well.
