This 2019 episode notes that the Catacombs contain the bones of an estimated 6 to 7 million people, and explains that their history is really two interconnected stories of mines and human remains.

Gustave Flaubert and the ‘Madame Bovary’ Trial
45:15

Elizabeth Bisland, Beyond the Trip Around the World
42:54

SYMHC Classics: Marie Laurencin
32:46