The Benedictine abbey of Saint-Louis-du-Temple in Vauhallan on the Saclay plateau towers over the valley of the Bièvre. The faithful go there for services sung in Gregorian chant, for a spiritual retreat, for craft courses, for its country produce, for a stop on the pilgrim route for Santiago de Compostella or to visit its two museums in the crypt:
- one of them devoted to Louise-Adélaïde-de-Bourbon-Condé, founder of the order and to mementos of the royal family, Louis XVI and Marie-Antoinette.
- the other to mother Geneviève Gallois, internationally renowned artist who created the astonishing stained glass in the abbey church.