"To be happy, stay hidden." - Yopie, Parisian cataphile

Ever since reading Jennifer Toth's The Mole People as a teen, I've been intrigued by the metropolitan underground. Cities teem with life, and change happens at a dizzying pace. But what lurks beneath the streets remains a mystery to many—it almost remains a realm lost to time. Yet, to think of this space as stagnant would be foolish: from Paris to New York City, the subterranean has a life and character all of its own. And if you look closely, you'll find traces of the urban centers on the surface—almost as though these spaces contain seeds of the personalities that thrive above ground.

National Geographic's Neil Shea did a sweeping tour of the Parisian underground, covering everything from the catacombs to the old quarries to the hand carved party rooms inhabited by cataphiles—"people who love the Paris underground." There are all sorts of spaces to be found beneath Paris—canals and reservoirs, crypts, bank vaults, wine cellars, quarries—and cataphiles claim them to party, perform, create artwork, do drugs and more. They explore, hook up, educate, and claim these forgotten places. They map them and create records though it seems that these spaces exist on the periphery of the surface world, which seems odd when you consider how much of the metropolis is drawn from the underground.

Paris sits on a labyrinth of tunnels, making it a porous city born from a wealth of gypsum and limestone deposits:

The Romans were the first to harvest the stone; their bathhouses, sculptures, and arena can still be found on the Île de la Cité and in the Latin Quarter. Over the centuries, as Roman Lutetia became Paris, quarrymen burrowed deeper and wider, carving out the stuff of the city's great buildings—the Louvre, for example, and Notre Dame. Open pits evolved into networks of underground galleries.

Initially, Shea tells us, these quarries were located outside of the city limits, but as the metropolis expanded, it gradually covered these pockets, so that now certain areas are potentially in danger of collapsing. The first such collapse occurred in 1774, and prompted King Louis XVI to commission a map of the quarries to aid in stabilization efforts as well as urban planning. However, smaller collapses have continued to occur: In 1961, 21 people were killed when an entire neighborhood disappeared into the earth.

There is sanctity, solitude, and beauty to be found underground as well. The old quarries were re-used as ossuaries—underground cemeteries turned tourist attractions, albeit limited ones today. It makes for a breathtaking image: thousands of bones stacked upon each other. In essence those who came before are literally supporting the city. Okay, so maybe not literally, but you get my drift. Shea also takes readers to a room built by cataphiles—with benches carved from stone and hollows for candles, it seems a perfect escape from the general hustle and bustle. And then there are the fabled places, such as the underground pond at the Opéra Garnier featured in Phantom of the Opera. It exists. There are fish who live there. According to Shea, opera workers feed them. These different aspects of the Parisian underground seem to reflect some of the city's personality: the ossuaries, the dusty quarries, the new uses of space speak to the traditions and cultures that are embedded in Parisian life, as does the interesting reuse and rediscovery of the spaces below the city streets.

What lurks below New York City? Alligators? Beautifully constructed and now abandoned subway platforms? Disused subway vaults? Mole people? Lost waterways, forgotten aqueducts and canals? All of this and more it seems. Most of New York City's infrastructure is underground, as this graphic from National Geographic shows. But, there is definitely more to the story than power and sewer lines. New York City may not be as old as Paris, but there are definite traces of our past and reflections of our present to be found underground. New York Times reporter Alan Feuer traveled twelve feet underground, through sewers in the Bronx, Manhattan, and Queens with urban explorers Erling Kagge and Steve Duncan. He waded through muck—the waters in the Bronx are "browner" than the waters in Queens, who knew?—and fecal matter to get to forgotten tunnels. They traced the path of Tibbetts Brook, a holdover from the undeveloped days of the island whose presence is now only found underground in the mapping of a sewer that follows the stream's path. It originated in Yonkers and flowed south to the Harlem River Ship Canal. But it's there—a reminder of the way our past helped shape out present.

The elaborate City Hall station built by Heinz and LeFarge, and now closed to the public, stands as a testament to a particular era in New York City. Before sweeping urban growth changed the face of the city, grand architecture in the Beaux-Arts style was the norm. And then there are the underground residents themselves—Toth's mole people, who have fashioned cities of their own in the subterranean maze of abandoned tunnels. New York City's underside is gray and winding, but there is an organization to it as well. The grid above reflects the grid below—streets follow the lay of the land, as in the case of Tibbets Brook and Canal Street. The social order below reflects the organization above.

Periodically, a telephone company van will block off a manhole not too far from my office, and workers will drop below the streets. I wonder if I could convince them to take me next time. I might have to change my shoes, though.