Paris , France ( CNN ) -- Beneath the streets of the City of Light lies a world draped in darkness and shrouded in silence . The tunnels are narrow , the ceilings are low and death is on display . The skulls and bones lining the walls , arranged in a macabre fashion , make up what is known as the Empire of the Dead -- the Catacombs of Paris . The catacombs snake below the city , a 321-kilometer ( 200-mile ) network of old quarries , caves and tunnels . Some Parisians are drawn to this largely uncharted territory -- a hidden network of adventure , discovery and even relaxation . They are known as 'cataphiles ' and the catacombs are their playground . It is a top-secret group . Catacomb entrances are known only to those daring enough to roam the networks on their own -- and break the law . Entering unauthorized sections of the catacombs is illegal and a police force is tasked with patrolling the tunnels , and caught cataphiles risk fines of up to 60 euros ( $ 73 ) . But for explorers like Loic Antoine-Gambeaud and his friends , it is a risk they are willing to take . `` I think it 's in the collective imagination . Everybody knows that there is something below Paris ; that something goes on that 's mysterious . But I do n't think many people have even an idea of what the underground is like , '' Antoine-Gambeaud said . For those who want to find out , but are not willing to take the risk of going in unsupervised , there is a legal , tourist-friendly public entrance to the catacombs off Place Denfert-Rochereau . Visitors from around the world will queue up to see death on display . `` I think people are fascinated with death , '' one visitor said . `` They do n't know what it 's about and you see all these bones stacked up , and the people that have come before us , and it 's fascinating . We 're trying to find our past and it 's crazy and gruesome and fun all at the same time . '' But experiencing the history of Paris in an orderly fashion is not the cataphiles ' style . Underground , there are plaques echoing the street names above etched into the walls , helping the cataphiles navigate . Often equipped only with head lamps and homemade maps , they explore the tunnels and ancient rooms , sometimes staying underground for days at a time . They throw parties , drink wine , or just relax in a silence they say ca n't be experienced anywhere else . The catacombs are a by-product of Paris ' early development . Builders dug deep underground to extract limestone to build Paris above ground . But the subterranean quarries that were formed proved to be a shaky foundation for the city , causing a number of streets to collapse and be swallowed up by the ground . Eventually , repairs and reinforcements were made , and to this day , the tunnels and quarries are still monitored for safety . The quarries went through several transformations throughout history . Over time , they have served as everything from hiding places for revolutionaries to mushroom farms . In the 18th century the Catacombs became known as the Empire of the Dead . Paris ' dead had been buried in cemeteries and beneath churches in the city center , but the number of bodies began to overwhelm the land , breaking through the walls of people 's cellars and causing major health concerns . So , beginning in the 1780s , the bodies were transferred in carriages at night to a new , final resting place in the old quarries . In those tunnels there are now the remains of more than six million people . And for the cataphiles , the life among the dead opens up new dreams and possibilities . `` It 's like an alternate reality , '' Antoine-Gambeaud said . `` You do n't have the same sort of social interaction with people as you do above . You are free to invent yourself again , to be somebody else . '' Bone people : The explorers of the Parisian catacombs .
Beneath the streets of the French Quarter is a hidden , macabre Parisian playground . The catacombs are also the last resting place for 100 million people . Adventurous Parisians use the underground network as a place to relax and relax . One said : You are free to invent yourself again , to be somebody else .