The Catacombs of Paris
This place has to be one of the creepiest places on this planet, even though it is now a government-regulated tourist attraction. Paris has a complex underground maze stretching over an area of more than 300 km right below the city. And in the narrow twisted lanes of this maze reside the remains of more than 6 million Parisians. In the 18th Century, when the epidemic plagued the citizens of Paris, the death toll increased at an alarming rate. So much so that even the cemeteries of Paris couldn’t accommodate the dead bodies. The city stank of dead bodies, especially after they littered the streets post floods. To solve this problem, the citizens of Paris started depositing these dead bodies in the underground spy network of Paris.