What are all of the skeleton bones from?

Question

Catacombs in Paris, France I had i had seen on Discovery Channel. I was in shock by all of the bones in the walkways. I think it ends up going a couple of kilometers to make it through with about 6 million bodies worth of bones below the surface. Adding up to more than the population of Paris itself.

Answer 1

http://en.wikipedia.org/wiki/Catacombs_o...

Answer 2

that's where they buried their dead year after year

decade after decade century after century they ran out

of room buried the dead anywhere they could in the catacombs