Illo: Andrew DeGraff

On one of the last busy evenings of Fashion Week, the suppertime clique that had turned up for the AnOther magazine dinner at the Fat Radish on Orchard was making the trek to the after-party. A breeze had split the night’s air. Most of the gang opted to walk, despite—or due to?—the hash brownies with which many, including The Observer, had topped off the meal.

Well, not everyone: Daphne Guinness, in heels that lifted her 10 feet toward God, cabbed it.

The gang sauntered over to the Bowery and, upon taking a left, entered meandering streets that looped like a child’s doodles—endless ovals of turns, each leading to an alleyway, a familiar passage, a dead end. We were looking for Apotheke. Finding it without a smart phone? Forget it, Nate. It’s Chinatown.

But we did have one, and so made our way to the elbow of Doyers and the swanky mixological wonder surrounded by kids, some on skateboards, many feigning confusion at not being on the list.

Inside, one found the same gridlock at the bar, but something was off. Everyone who had been at the dinner, Dasha Zhukova and Olympia Scarry and AnOther editor Jefferson Hack … where had they gone? Did they skip out for some other bash? What were we missing?

“Should we check out the downstairs?” our friend said out of nowhere, in a whisper.

So that was it. In a few moments we had ducked behind the bar, wedged through a tiny entrance, dodged the hanging pots and pans lining a maze of storage tunnels, and found ourselves in a low-ceilinged but expansive lair. This was Pulqueria—a forbidden city of nightlife fever dreams. One of those hidden places you stumble upon one night and forever after wonder where exactly it was, or whether it existed at all. To judge by the faces of those who had made it inside, the joy, the hardly hidden smugness at their discovery, it might have well been El Dorado.

Pulqueria is just the most recent night spot to upgrade its original offerings with a tiny, “hush-hush” venue-within-a-venue. With space in Manhattan running out and community boards in a prudish state of mind, well, you might as well dig down on the space you’ve got rather than try to expand outward.

As if we didn’t have enough nighttime anxieties, what with all of those velvet ropes and stony faced doormen. At any given time, at any bar in the city, there may be somewhere directly beneath you—or above?—where people are having a better time than you. How can you enjoy yourself when the real party is likely elsewhere? Look left, then right—is something missing? Start asking around about the other place, you know, that place. You know, the place.

Each sneaky spot’s got its own variation on the theme, but the defining characteristics tend to stay the same. These places are dark. The ceilings are low and the drinks—sorry, the mixologist-curated creations—are priced sky-high. True, none of them are secret for long, thanks to Twitter, streetsmart blogs and, ahem, New York newspapers. But we all know that’s not the point. They feel secret once you’re there, and that’s often enough to seal the deal.

Pulqueria joins an impressive roster of places in Manhattan peddling booze on the down low. There’s PDT, on St. Marks Place, which made a bit of a splash when it opened inside the Crif Dogs weiner shop in 2007. The charm there comes from an entry ritual worthy of Clark Kent: you slide into the red phone booth in the corner of the greasy spoon, pick up the receiver, and ask if there’s a table available. Which brings up a nice irony: if you see a phone booth in Manhattan these days, you’ll have a better chance of finding a drink than a dial tone.

The contrast between boardwalk grub and high-end gin is key here, and other joints are determined to milk the same clash. The Back Room—a bit of a misnomer, given that it actually has no “front”—lies at the end of an alley and past a sign that reads “Lower East Side Toy Co.” Those seeking the boîte Second Floor on Clinton must brave the galloping herd of tequila fiends who frequent the decidedly rowdier Barramundi. Then, there are the periodical pop-ups: Simonez Wolf’s celebrated Madame Wong’s party has taken up semipermanent residence at Jobee and, now, Red Egg—anonymous Chinatown eateries by day, celeb-heavy hot spots at night.

Bathtub Gin, a recently opened 1920s-styled watering hole, is accessed through an innocuous-looking place called Stone Street Coffee Company. Walk past the line of French presses (they actually serve coffee!) and push the wall. A red glow spills through the cracks. There is actually a battub inside. “The whole point was people come to have coffee during the day not knowing what’s behind there, and you open the door to a whole new world,” Dave Oz, the manager and owner, told The Observer.

Not that these two-faced venues are anything new. The Prohibition-era speakeasy begat the gay bar back room, and in the disco days, clubgoers sought out small spaces in clubs in which do things in private. Bathrooms always work, of course, but there were other, more comfortable locales, namely dead area behind walls, and P.V.C.-laden industrial corners. Rather than policing every forgotten pocket, the thinking went, why not stick a few bottles of liquor and a bartender down there, sweep up the soot, throw out the warped two-by-fours, and make things official?

For example: the Strategic Tao Group at the Dream Downtown hired Nur Khan to take the storage space beneath the ground floor and whip up a super tiny, super exclusive spot. This became Electric Room, the toast of last month’s Fashion Week, despite the fact that guests have to brave a steep and entirely unglamorous truck ramp that tunnels beneath the building. On its first night serving booze, Adrien Grenier christened the walkway by being the first person to trip.

And deep under Don Hill’s, a now-closed west Soho rock joint Mr. Khan reopened with Paul Sevigny in September 2010, an even tinier place, unknown to most everybody dancing to the Misshapes upstairs. If you got past the security personnel standing conspicuously in a nook by the raised V.I.P. lounge, a rickety staircase would take you to a cement cavern lined occasionally with metal racks. It was a space reserved for bands pre- and postperformance, and also a super exclusive spot for those fed up with the body-on-body scrum of the dance floor.

Venturing beyond that, the truly adventurous enter what appeared to be a mix between a boiler room and Turkish bath—just a box, really, the size of a tiny Manhattan bedroom. The last time The Observer ventured in was just a few weeks before Don Hill’s shut its doors for good, and we chain-smoked as a young man who claimed to be a doctor described the intricacies of open heart surgery. Good times.

Two of the city’s most conventional secret rooms lie directly adjacent to each other at the juncture of Kenmare and Lafayette: Cafe Select and La Esquina. The former’s already small enough that an even more minuscule hidden space within would seem unnecessary, but have no doubt. Make a right at the boiler room, and there you are.

Then there’s the backroom at La Esquina, hidden beneath a taco joint that came to the block already dinged up, as if it had been there for years.

“It’s almost the hardest place to work,” said a former employee, “because people think they’ve already made it in, and then you have to turn them away.”