6 million people under Paris, and only 2 million living above ground in the city today! (intra-muros of course). A very strange but interesting visit. apparently the bones were all thrown down there in heaps, just to get them out of the Over crowded cemeteries, which were overflowing with the dead. A very practical approach. But whoever decided, much later, to stack them up into the walls of thigh bones interspersed with decorative patterns made of anonymous skulls must have been an interesting character...