The Church of St. Bernadette is the modern church across the river from the main basilicas in the Sanctuary of Our Lady of Lourdes. It marks the spot where Bernadette Soubirous stood during the final apparition, giving it a clear place in the pilgrimage landscape even though the building is much newer than the older shrines.
Visit it as part of a walk through the sanctuary precinct, especially if you want to understand how the sites around the Grotto fit together.