UX’s most sensational caper (to be revealed so far, at least) was completed in 2006. A cadre spent months infiltrating the Pantheon, 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 Pantheon’s 19th- century clock, which had not chimed since the 1960s. Those in the neighborhood must have been shocked to hear the clock sound for the first time in decades: the hour, the half hour, the quarter hour.
UX (“Urban eXperiment”) is an artist collective that have been surreptitiously infiltrating, restoring, and maintaining abandoned cultural works in Paris for decades. I highly recommend reading this Wired article about UX.