Montmartre Walking Tour Sacrée Coeur Paris

The Sacré-Cœur Basilica remains a brilliant white against the Parisian skyline because of its unique construction material. It was built using travertine stone from a quarry in Château-Landon that contains high levels of calcite. When this stone comes into contact with rainwater, it releases a substance that acts as a natural bleach, ensuring the building continually cleans itself and maintains its iconic, radiant appearance.