It's the hottest, most talked about art show in New York - and almost no one even knows where it is.
With a huge space and 103 of the hippest contemporary artists participating, "The Underbelly Project" sounds like a powerhouse production at the Met or MoMA.
But while the Big Apple may have seen most things in the art world, this is different.
Illegally located somewhere deep underground in an abandoned station of the New York Subway system, "Underbelly" consists of graffiti art by a who's who of the street genre's leading exponents.
Starting in 2009, they worked clandestinely, with almost military discipline, to elude the authorities, navigate pitch-black tunnels, paint, and resurface.
Their work completed, the artists sealed access to the subterranean complex and abandoned their mysterious outpourings. The show's website, www.theunderbellyproject.com, has for the last week displayed nothing more than a brief written introduction against the flashing background of empty tunnels.
It "defies every norm of the gallery scene," wrote Jasper Rees, one of the few outsiders allowed to glimpse the phantom show and who revealed its existence October 31 in The New York Times.
"Collectors can't buy the art," Rees says. "The public can't see it. And the only people with a chance of stumbling across it are the urban explorers who prowl the city's hidden infrastructure or employees of the Metropolitan Transport Authority."
Photos posted by the Times and on street art blogs show dramatic, wild works executed in appalling conditions of dust, damp and darkness broken only by camping lanterns.
Slogans like "We own the night" give way to abstract creations, surreal human forms, and ghoulish apparitions of rats and skulls.
But what created an instant legend was the idea of entombing the work.
"Even if any of us wanted to go back (and I do), even if we could remember how to get there (and I don't), we can't," writes Michael "RJ" Rushmore, who was taken to photograph the site, for his blog vandalog.com. "'The Underbelly Project' has become a time capsule."
- New York's ghost stations -
A guessing game is underway across art websites about the location of this ultimate underground experience.
Many New Yorkers are unaware of the archipelago of abandoned stations, platforms and tracks, or trackless tunnels running parallel to the visible Subway system. There are nine complete stations alone, according to the website Abandoned Stations.
Charles Seaton, a spokesman for the Metropolitan Transport Authority, or MTA, confirmed to AFP only that "it is a closed station. All I can tell you is that it's in Brooklyn."
The war between the MTA and graffiti vandals has been going on for decades. Spraying of subway trains got so out of control in the 1970s and '80s that many carriages were almost inundated in "tags."
"Tagging" continues today, but the MTA immediately pulls those cars out of service, starving would-be artists of the notoriety they crave.
And Seaton said the "Underbelly Project" was not being taken lightly.
"Trespassing is against the law, as is vandalism. Anyone caught in connection with this incident is subject to arrest," Seaton warned.
That illegality is exactly what drove the "Underbelly Project" as it sought to reclaim graffiti's daredevil roots and, in the words of the project's website, create an "elusive pirate treasure of contemporary art."
The show also sought to roll back the commercialization and gentrification of graffiti.
This is an age when street artists like JR and Britain's Banksy have global recognition and collectors are pouring in money.
Next year, Los Angeles' trendy Museum of Contemporary Art plans a major retrospective of graffiti called "Art in the Streets." And last year, the Cartier Foundation in Paris had its own "Born in the Streets" show.
So taking their spray cans four storeys under New York was about as far from the chic gallery scene that "Underbelly's" artists could get.
As, Workhorse, one of the two leaders of the project, told Rees: "If you go in there and break your neck, nobody's going to hear you scream."
But, like the incomplete map of the Subway system, not everything is straightforward.
Although they worked in secret, many of the artists taking part in the project are literally stars in the worldwide graffiti community.
LTV Squad.com, another blog, cites a "'who's who' of the art world," including Sane, Swoon, Roa, Posterchild, Faile, F5, Smells, and Cash4. "'The Underbelly Project' is perhaps the biggest, boldest art project of its kind ever created within NYC."
That kind of hype is making some graffiti aficionados skeptical.
"The artists talked about not making this a mainstream thing with the galleries, but in a sense it falls right into that," said Eric Felisbret, a former tagger who runs the influential www.at149st.com website and who recently published "Graffiti New York," a photo history.
"It helps reinforce their street cred and that's what gets buyers interested in this form of art. It builds the mystique," Felisbret told AFP.
He added drily: "If they wanted to be secret, they wouldn't have contacted the Times."
Photographs of the "Underbelly Project" can be viewed at: http://www.nytimes.com/slideshow/2010/10/29/arts/design/20101101-underbelly-ss.html