Paris was a wonderful place to visit (although I wish I tried harder in high school French class now) and has some amazing and historical sites, but my favorite by far were the Catacombs.
This underground labyrinth was formed by mining during the 1st-12th century for the limestone to use as build material. In fact much of the city was built with this very limestone. Well these mines were haphazardly dug and left a vast cave system that started to collapse in the late 1700’s as the city moved over them. They had to be reinforced and at the same time the city cemeteries were overflowing due to 13 centuries of dead bodies. It got so bad that a cemetery wall broke and spilled bodies into several cellars. YUCK!
City officials decided to move the bodies (over 6 million) into the catacombs and one of the employees stacked the femurs and skulls in an artistic manner. Public visits have been occurring since the beginning of the 1800’s. As you walk through you get a history of the mines, collapses, and reinforcements before you get to the ossuary and see all the bones. My mere words can not describe how many bones there are, how chilling the experience was, and how much I can not stop talking about it. One recommendation I have is to get the audio guide, since it give you a lot of information you would not have had otherwise.