Perched high on the Butte Montmartre, the Basilique du Sacré-Coeur is one of Paris's most emblematic monuments. And just in time for the Journées du Patrimoine, this unusual church reveals its secrets with a special program on the weekend of September 20 and 21, 2025. This year, we're off to discover the organ building site as the monument is given a new lease of life.