Quote by Edward Rutherfurd

“The hill was mainly composed of the soft stone material known as gypsum which possessed two qualities: first, it would slowly dissolve in water and was thus a poor foundation for any large building. Second, when heated, after giving off steam, it could easily be ground into the powder from which white plaster was made. For that reason, men had been burying into the hill of Montmartre for centuries to extract the gypsum. So famous had these quarrying's become, that now, even across the ocean, white plaster had come to be known as Plaster of Paris. When the builders of Sacre Coeur began their task therefore, they found that the underlying terrain was not only soft, but so honeycombed with mineshafts and tunnels that had the great building been placed directly upon it, the entire hill would have surely collapsed, leaving the church in a stupendous sinkhole. The solution had been very French, a combination of elegant logic and vast ambition: 83 gigantic shafts were dug, each over 100 feet deep filled with concrete. Upon these mighty columns, like a huge box, almost as deep as the church above, the crypt was constructed as a platform. This work alone had taken almost a decade, and by the end of it, even those who hated the project would remark with rye amusement: 'Montmartre isn't holding up the church, it's the church that's holding up Montmartre'.”

Quote by Edward Rutherfurd