This one is somewhat macabre, but it’s still something worth seeing. Under Paris are the infamous catacombs. I had a vague idea what it would be like, but it was an entire order of magnitude more intense than I expected! I thought, perhaps, there would be a few places with a whole bunch of bones, but it just went on and on and on and on. You have no idea (unless you have been there too). There were hundreds of yards of one kind of human bone followed by another hundred yards of another kind of bone. They used skulls for all sorts of decorations, including this embedded heart.