This article was taken from the March 2012 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.

Thirty years ago, in the dead of night, A group of six Parisian teenagers pulled off what would prove to be a fateful theft.

They met at a small café near the Eiffel Tower to review their plans, before heading out into the dark. Lifting a grate from the street, they descended a ladder to a tunnel, an unlit concrete passageway carrying a cable off into the void. They followed the cable to its source: the basement of the Ministry of Telecommunications. Horizontal bars blocked their way, but the skinny teens managed to wedge themselves through and climb to the building's ground floor. There they found three keyrings in the security office and a logbook indicating that the guards were on their rounds.


But the guards were nowhere to be seen. The six interlopers combed the building for hours, encountering no one, until they found what they were looking for at the bottom of a desk drawer -- maps of the ministry's city-wide network of tunnels. They took one copy of each map, then returned the keys to the security office.

Heaving the ministry's grand front door ajar, they peeked outside; no police, no passersby, no problem. They exited onto the empty Avenue de Ségur and walked home as the Sun rose. The mission had been so easy that one of the youths, Natacha, asked herself if she had dreamed it. No, she concluded: "In a dream, it would have been more complicated."

Read next Gallery: Urban eXperiment: The new French underground Gallery Gallery: Urban eXperiment: The new French underground

This stealthy undertaking was not an act of robbery or espionage but rather a crucial operation in what would become an association called UX -- "Urban eXperiment". UX resemble an artist's collective, but far from being avant-garde -- confronting audiences by pushing the boundaries of the new -- its only audience is itself. More surprising still, its work is often radically conservative, intemperate in its devotion to the old. Through meticulous infiltration, UX members have carried out acts of cultural preservation and repair, with an ethos of "restoring those invisible parts of our patrimony that the government has abandoned or doesn't have the means to maintain".

The group claims to have conducted 15 such covert restorations, often in centuries-old spaces, across Paris.


What has made much of this work possible is UX's mastery, established 30 years ago and refined since, of the city's network of underground passageways -- hundreds of kilometres of interconnected telecom, electricity and water tunnels, sewers, catacombs, subways and centuries-old quarries. Like computer hackers who crack digital networks and surreptitiously take control of key machines, members of UX carry out clandestine missions throughout Paris's supposedly secure underground tunnels and rooms.

The group routinely uses the tunnels to access restoration sites and stage film festivals, for example, in the disused basements of government buildings.

UX's most sensational caper (or, at least, revealed so far) happened in 2006. A dedicated cadre spent months infiltrating the

Panthéon, the grand structure in Paris that houses the remains of France's most cherished citizens. Eight restorers built their own secret workshop in a storeroom, which they wired for electricity and internet access and outfitted with armchairs, tools, a fridge and a hot plate. During the course of a year, they painstakingly restored the Panthéon's 19th-century clock. The neighbourhood must have been shocked to hear the clock sound for the first time in decades: on the hour, the half-hour, the quarter-hour.


Eight years ago, the French government didn't know UX existed.

When their exploits first trickled out into the press, the group's members were deemed by some to be dangerous outlaws, thieves, even potential inspiration for terrorists. Still, a few officials can't conceal their admiration. Mention UX to Sylvie Gautron of the Paris police -- her speciality is monitoring the city's old quarries -- and her face breaks into a smile. In an era when ubiquitous GPS and microprecise mapping threaten to squeeze all the mystery from our great world cities, UX seems to know, and indeed to own, a deeper, hidden layer of Paris. It claims the entire city, above- and below-ground, as its canvas; its members say they can access every last government building, every narrow telecom tunnel. Does Gautron believe this? "It's possible," she says. "Everything they do is very intense."

According to Lazar Kunstmann, it is not hard to steal a Picasso.

One of UX's early members and the group's unofficial spokesman, Kunstmann -- the name is almost certainly a pseudonym, given its German meaning "Art man" -- is forty-ish, bald, warm and witty.

Downing espressos in the back room of a student café, he discusses the spectacular theft in May 2010 of €100 million (£83 million) worth of paintings from the Museum of Modern Art of the City of Paris. He disputes the contention of a police spokesperson that this was a sophisticated operation.

According to an article published in Le Monde, a solitary individual unscrewed a window frame at 3:50am, cut a padlock from a gate, and strode through the galleries, lifting single works by Léger, Braque, Matisse, Modigliani and Picasso. "The thief was perfectly informed," the officer told the newspaper. If he hadn't known the window had a vibration detector, he would've just broken it. If he hadn't known the alarm and part of the security system were broken, he wouldn't have wandered throughout the museum. If he hadn't known the schedule of night rounds, he wouldn't have arrived in the middle of the longest quiet period.

Impressive, right? Not quite, says Kunstmann. "He ascertained that nothing was working," he sighs. "The exterior is full of graffiti artists, homeless people and crack smokers," he goes on.

This would have made it easy to blend in and surreptitiously watch the windows all night, observing how the guards circulated.

But was it UX that stole the paintings from the Museum of Modern Art? Wouldn't that be the perfect way to alert the French to the appalling job their government does protecting national treasures?

Kunstmann denies it with a convincing curtness. "That," he says, "is not our style."

UX has made a study of museum security, in keeping with its concern for Paris's vulnerable treasures -- a concern not always shared by the city's major cultural institutions. Once, after a UX member discovered security lapses in a major museum, she wrote a memo detailing them -- leaving it on the security director's desk in the middle of the night. Rather than fix the problems, the director went to the police, demanding they press charges against the perpetrators. (The police declined, though they did warn UX to slow down.) Kunstmann says he is sure that nothing has changed at the Museum of Modern Art since the break-in and security remains just as shoddy as ever.

Kunstmann has a gloomy view of contemporary civilisation, and in his eyes this affair illustrates many of its worst faults -- its fatalism, complacency, ignorance, parochialism and negligence.

French officials, he says, bother to protect and restore only the patrimony adored by millions -- the Louvre, for example. Lesser-known sites are neglected, and if they happen to be out of public view -- underground, say -- they disintegrate totally, even when all that's needed is a hundred-euro repair. UX tends the black sheep: the odd, the unloved, the forgotten artefacts of French civilisation.

It's difficult, though, to give an accounting of just how extensive those labours of love have been: The group cherishes its secrecy, and its known successes have been revealed only inadvertently. The public learned of the group's underground cinema only after a member's ex-girlfriend told the police. Reporters heard about the Panthéon operation because UX members erred in supposing they could safely invite the building's director to maintain his newly fixed clock.

Based on members' interests, UX has developed a cellular structure, with subgroups specialising in cartography, infiltration, tunnelling, masonry, internal communications, archiving, restoration and cultural programming. Its 100-odd members are free to change roles and are given access to all tools at the group's disposal. There is no manifesto, no charter, no bylaws -- save that all members preserve its secrecy. Membership is by invitation only; when the group notices people already engaged in UX-like activities, they discuss joining forces. Although there is no membership fee, members contribute what they can to projects.

The first UX experiment, in September 1981, was an accidental one. A Parisian schoolboy named Andrei was trying to impress a couple of older classmates, boasting that he and his friend Peter often snuck into places and were about to hit the Panthéon. Andrei got in so deep with his boast that to save face he had to follow through -- with his new friends in tow. They hid out inside the building until it closed. Their nocturnal occupation turned out to be shockingly easy -- they encountered no guards or alarms -- and the experience electrified them. They thought: what else could we do?

Kunstmann, a classmate of Andrei and Peter's, joined the group early on. They quickly branched out from mere infiltration.

Obtaining the tunnel maps from the Ministry of Telecommunications and other sources greatly expanded their access. Many Parisian buildings connect to these passages through their basements, which are as badly secured as the tunnels themselves. Most officials, Kunstmann says, act as if they believe in the absurd principle that tunnel access is forbidden, thus people don't go there. This, he adds, is "a flawless and very practical conclusion, because if people don't go there, then it's unnecessary to do more than lock the entrances."

It's understandable why French officials are so complacent.

Finding an unlocked entrance, without UX's know-how, requires a 45-minute walk from the nearest Métro station. UX has access to dry and spacious tunnel networks, but the more easily entered ones are often tiny and half-flooded.

In some places, UX has been able to create covert connections between networks, using (among other tricks) an invention they call the rolling basin. This is a passage in the bottom of a tunnel that appears to be a grate with water under it; in fact, both grate and water are part of a movable tray on rollers -- a trapdoor to another tunnel in a different network. The tray itself is made of concrete, so even if someone raps it with a stick, it sounds solid.

This extra freedom and access helps to enable the UX to organise, among other things, clandestine theatre productions and film festivals. On a typical festival evening, they screen at least two films that they feel share a tenuous yet provocative connection. They don't explain the connection, leaving it up to the audience to discover it. One summer, the group mounted a film festival devoted to the theme of "urban deserts" -- the forgotten and underused spaces in a city. They naturally decided the ideal venue for such a festival would be in just such an abandoned site.

They chose a room beneath the Palais de Chaillot they'd long known of and enjoyed unlimited access to. The building was then home to Paris's famous Cinémathèque Française, making it doubly appropriate. They set up a bar, a dining room, a series of salons and a small screening room, and they held festivals there every summer for years. "Every neighbourhood cinema should look like that," says Kunstmann.

The restoration of the Panthéon clock was carried out by a UX subgroup called Untergunther, whose members are devoted specifically to restoration. The Panthéon was a particularly resonant choice of site, since it's where UX began, and the group had surreptitiously screened films, exhibited art and mounted plays there. During one such event in 2005, UX cofounder Jean-Baptiste Viot (one of the few members who uses his real name) took a close look at the building's defunct Wagner clock, an engineering marvel from the 19th century. Viot had admired the Wagner ever since he first visited the building. He had meanwhile become a professional horologist working for Swiss watch firm Breguet. That September, Viot persuaded seven other UX members to join him in repairing the clock. They'd been contemplating the project for years, but now it seemed urgent: oxidation had so crippled the works that they would soon become impossible to fix without recreating, rather than restoring, almost every part. "That wouldn't be a restored clock, but a facsimile," Kunstmann says.

As the project began, it took on an almost mystical significance for the team. Paris, as they saw it, was once the centre of Western civilisation; the Latin Quarter was Paris's intellectual centre; the Panthéon stands in the Latin Quarter; and in its interior lay a clock, beating like a heart, until it suddenly was silenced.

Untergunther wanted to restart the heart of the world. The eight shifted all their free time to the project.

They first established a workshop high up in the building, just below its dome, on a floor where no one went any more -- "a sort of floating space," says Kunstmann. "It looked down on all of Paris from a height of 15 storeys. From the outside it resembled a kind of flying saucer; from the inside, a bunker." The workshop was outfitted with eight overstuffed armchairs, a table, bookshelves, a minibar and red velvet drapes to moderate the ambient temperature. "Every element had been conceived to fold up into wooden crates, like the ones visible throughout the monument," Kunstmann says. In the dead of night, they climbed endless stairs, hauling up the lumber, drills, saws and clock repair equipment. They updated the workshop's outdated electrical wiring and spent €4,000 on materials. On the terrace outside they set up a vegetable garden.

Like at the Museum of Modern Art, where a thief made off with millions in precious art with shocking ease, security at the Panthéon was substandard. "No one worried over people entering and leaving the Pantheon by the front door," Kunstmann says.

Nevertheless, the eight equipped themselves with official-looking fake badges. Each had a photograph, a microchip, a hologram of the monument and a barcode that was "totally useless but impressive".

Once the workshop was complete, the eight got to work. The first step was to understand how the clock had become so degraded -- "a sort of autopsy," Kunstmann says. What they discovered looked like sabotage. It appeared that someone, presumably a Pantheon employee tired of winding the clock once a week, had bludgeoned the escape wheel (a toothed wheel that manages the clock's rotation) with an iron bar.

They brought the clock's mechanism up to the workshop. Viot trained the group in clock repair. First, they cleaned it: three litres of water were carried up from the public bathrooms on the ground floor and mixed with 500g of soluble soap, 25cl of ammonia and a tablespoon of oxalic acid. With this solution the group scrubbed and polished every surface. Then they repaired the mechanism's glass cabinet, replaced broken pulleys and cables and recreated the escape wheel and missing parts such as the pendulum bob.

As soon as it was completed, in late summer 2006, UX told the Pantheon about the successful operation. They figured the administration would happily take credit for the restoration itself and that the staff would take over the job of maintaining the clock. They notified the building's administrator Bernard Jeannot but were startled when he refused to believe their story. They were even more shocked when, after they showed him their workshop ("I think I need to sit down," he murmured), the administration decided to sue UX, at one point seeking up to a year of jail time and almost €50,000 in damages. Jeannot's then-deputy, Pascal Monnet, now the Pantheon's director, went so far as to hire a clockmaker to restore the clock to its previous condition. But the clockmaker refused to do more than disengage the escape wheel, the very part that had been sabotaged the first time. UX returned shortly after to take the wheel for safekeeping, in the hope that someday a more enlightened administration will welcome its return.

The government lost its lawsuit. It filed another, which it also lost. There is no law in France, it turns out, against the improvement of clocks. But the clock is still immobile today, its hands frozen at 10:51.

UX are not rebels, guerrillas or freedom fighters. They didn't repair the clock to embarrass the state, nor do they entertain dreams of overthrowing it. Everything they do is intended for their own consumption. If they can be accused of anything, it's narcissism. The group is partly responsible for the fact that it is misunderstood. Its members acknowledge that most of its external communications are intended as misdirection.

When asked why they care about these places, Kunstmann answers with questions of his own. "Do you have plants in your home?" he asks. "Do you water them every day? Why do you water them?

Because," he continues, "otherwise they're ratty little dead things." Their goal, he says, isn't necessarily to make all these things function once again. "If we restore a bomb shelter, we're certainly not hoping for new bombardments so people can use it again. If we restore an early 20th-century subway station, we don't imagine Electricité de France will ask us to transform 200,000 volts to 20,000. No, we just want to get as close as possible to a functioning state."

UX has a simple reason for keeping the sites a secret even after it has finished restoring them: the same anonymity that originally deprived them of caretakers "is paradoxically what's going to protect them afterward" from looters and graffiti, Kunstmann says.

They know they'll never get to the vast majority of interesting sites that need restoration. Yet, "despite all that, the satisfaction of knowing that some, maybe a tiny fraction, won't disappear because we'll have been able to restore them is an extremely great satisfaction."

Pressed on UX's current projects, Kunstmann reveals little. He does say, however, that one site is "below ground, in the south of Paris. It totally contradicts the history of the building above it.

It's history in reverse; the site was dedicated to an activity, structures were placed there, but the site had been dedicated to this [other] activity for a long time."


Where is he describing? Did counterfeiters once operate out of the basement of the Paris Mint? Was the Saint-Sulpice church founded on the site of a pagan temple? All of Paris seems ripe with possibility: every keyhole a peephole, every tunnel a passageway, every building a theatre.

While this story was closing, a colleague needed to reach Kunstmann about a fact-checking question. He had told her to call "any time," so she got in touch. When he picked up the phone, he was panting -- from moving a couch, he said. She asked her question: when the clock had stopped chiming after the repair, what time remained frozen on its face? Kunstmann was in the Panthéon at that very moment. "Hold on," he said. "I'll look."

Jon Lackman is a journalist and art historian (jonlackman.com)