There is a heavy fine for those who are caught, but people do get in and take photos, paint murals, or draw maps of the catacombs. Word has it that police found a complete underground cinema a few years ago.
We fancied adventure, not getting lost on an illegal labyrinth hike. Luckily there is a legal way to get in. An area of about 2km is open to the public, but be prepared. It has the bones of about six million people stored in it.
Around 1800, the cemeteries in Paris were so overcrowded that corpses were not being properly buried because of lack of space. Bodies contaminated groundwater and spread disease in the heavily populated city. It was decided the cemeteries with millions of skeletons should be cleaned out and transported to the catacombs.
This was done very respectfully. The cemeteries were blessed and, over two years, the remains were dug up. The bones were transported at night, accompanied by priests, to the catacombs. In the next 30 years, all human remains went to this area.
A little reluctant, but feeling it was impossible to say no to the opportunity to see such a sight, we got our ticket to Denfert-Rochereau Ossuary. Despite the warning sign at the entrance - "Stop, this is the empire of death" - we descended 130 steps down a simple concrete stairway.
What we saw was unimaginable and breathtaking. Long, straight, cramped corridors with bones neatly stacked along the walls: all the same types of bones together. For hundreds of metres we were looking at the ends of femurs, tibias and fibulas, stacked up to the ceiling.
Some of these walls of bones were decorated with lines of skulls. Walking through, it felt like we were being followed by hundreds of hollow eyes. There were even skulls put together in the shape of a heart.
The Bible verses, proverbs and folk sayings written along the corridors make this journey amazing, normal and ghostly at the same time. It's creepy, yes - but wandering around here somehow feels okay though.
After all, everybody has a final destination.
CHECKLIST
Getting there: Emirates flies from Auckland connecting with Paris from their main hub in Dubai.
Further information: See catacombes-de-paris.fr.