Paris, my true love, over the years I have explored so much of what you have to offer. I repeatedly return to wander through the charming streets among the sharply dressed locals and munch on endless croissants. But this time I dug deeper… much deeper… into the bowels of the city, in fact.

Among the lesser-known tourism spots in Paris are the catacombs, far below the street level. When I visited my fave city two years ago, I stumbled upon the site by happenstance. I saw a line of people wrapping around the block after I had been wandering around nearby Montparnasse Cemetery, which also is definitely worth a stop. It’s the resting place of Jean-Paul Sartre, Simone de Beauvoir and Samuel Beckett, among others.

I asked the people in line what they were waiting for and immediately jumped in line myself when I heard it was for the Catacombs of Paris, containing the remains of about six million people… that kind of wacky historical stuff is right up my alley. But after 10 minutes in line, a worker came back and informed us that admissions close in half an hour and they estimate the person right in front of me will be the last to get in. He said the rest of us should return the next day. I became incredibly grumpy because it was my last day in Paris and I couldn’t return the following day, so I vowed to make the catacombs a priority the next time I was in town. Boy am I glad I did.

The self-guided tour begins by descending a single-person-width spiral staircase with a low ceiling. The catacombs started being used in the late 1700s when people were far smaller, so the narrow clearance made even my petite self a bit conscious of my size. The seemingly endless stairs taking me deeper and deeper into the dark underground (OK, about 130 steps, 65 feet underground) also produced an eerie feeling by the time I got about halfway down. But at that point, the only way to go is forward.

The space was first used as a limestone quarry, and came into play as an ossuary — or bone storage area — following a quarry cave-in and the city realizing it was running out of above-ground cemetery space. To stop the spread of disease from water flowing through the cemeteries, millions of bones were relocated to the catacombs. They now contain about 186 miles of tunnels and the ossuary only takes up a tiny portion, despite its vastness. The tunnels are dark and wet, understandably. Markers exist throughout with dates, showing just how old the space is and how long bones have been there.

And site workers carved interesting sculptures into portions of the catacombs.

But really, the reason everyone’s there is for the bones. Piles and piles of human bones. Femurs stacked neatly like blocks, skulls offering eerie, gaping glances.

You can literally reach out and touch centuries-old bones that all tell a person’s story (but don’t touch them and don’t use flash photography, both of which deteriorate the bones). It’s incredible to think about these people’s lives and what led to their deaths. Like this skull with the hole through the forehead. It’s hard to say if that hole contributed to death or if it happened later, but I chose to say, “Yeah, I don’t think that ended well.”

The thought of being surrounded by human bones didn’t freak me out in the least. Neither did the carving reading, “Arrete! C’est ici l’Empire de Mort” or, “Stop! This is the Empire of the Dead.” You know what did freak me out? Reading the informational placards and learning that catacombs workers died during tunnel cave-ins. That’s also why there aren’t many tall, heavy buildings over the tunnel system. Ummm… cave-ins. Right. That was enough to make my heart start racing as I looked behind me, peeked ahead, and quickly tried to assess the best escape route should a sinkhole mysteriously open and cause millions of pounds of concrete, crepes and tourists to pile onto me. I realized there was nothing I could do at that point and that if I were to die in a catacomb collapse, that would be fate’s truly crazy method of sending me out with a bang. So I forged on.

Most people will never get this up close and personal with real human bones in their lifetime. Where else can you see the intricate web left in a dried-out bone where marrow one existed? Look at the beautiful complexity of the human body! If you ask me, it’s incredible.

The catacombs truly are one of the more memorable experiences I’ve had in Paris. I recommend everyone musters up their courage and takes a visit to the tunnels. Yes, you may want to snap a few goofy photos pretending to be freaked out (or maybe you really are freaked out), but in the right mindset, it’s an experience of a lifetime.