Intrepid Parisians have been taking the concept of urban exploration to new heights—or depths, rather, as explained in this Guardian story:

Paris's new slant on underground moviesThere are, at most, 15 of them. Their ages range from 19 to 42, their professions from nurse to window dresser, mason to film director. And in a cave beneath the streets of Paris, they built a subterranean cinema whose discovery this week sent the city's police into a frenzy.

"They freaked out completely," Lazar, their spokesman, said happily. "They called in the bomb squad, the sniffer dogs, army security, the anti-terrorist squad, the serious crimes unit. They said it was skinheads or subversives. They got it on to national TV news. They hadn't a clue"...

Huddled round a table in an anonymous Latin Quarter bar, the group's members—of whom only Lazar wanted to be named—relate past exploits: rock concerts for up to 4,000 people in old underground quarries; 2am projections in a locked film theatre; art and photo exhibitions in supposedly sealed-off subterranean galleries.  [full story]

I was familiar with the idea of urban exploration already, where people explore forgotten, sealed-off, or off-limits reaches of a city's or university's infrastructure—frequently trespassing in the process. But this is just mind-bogglingly cool. I wonder if anything of the sort is happening in New York? I wonder if the authorities here are now on the alert?