Graeme Wood in Culture + Travel, reproduced on his own website:
Residents of Vidracco (pop. 500) knew the newcomers were different. Since 1977, they had been showing up one-by-one in the little Piedmontese valley, marching in from Turin like bugs following a trail of syrup. They kept to themselves. Their chitchat, when it came, zoomed right past the commonplace – nothing on the latest Juventus game, or the sorry state of farming in the valley. Instead, they spoke eagerly of “esoteric physics,” astral-plane travel, and Vidracco’s remarkable “synchronic energy lines,” supposedly unique on earth. And they rarely came out at night.
One day in 1992, Vidracco found out why. Backed by carabinieri and motivated by a tip, a magistrate showed up and demanded that the newcomers unlock a nondescript wooden door in the side of the mountain, next to their compound (called “Damanhur,” after the ancient Egyptian city). Inside, a cramped passage led to a section of wall decorated in pharaonic themes. The Damanhurians pointed a garage door opener at the flat stone surface, and clicked its button. Gears whirred, and a wall-section fell away.
Damanhur’s handful of citizens – dozens at first, but by now 330 — had been working in shifts, under cover of darkness, scratching at the earth with picks and shovels, and building shrines deep in the steep, forested mountain. Behind a series of false walls lay a revelation as mysterious as King Tut’s tomb, but grander — as ethereal as the Sistine Chapel, but weirder. In all, they had dug out over 8000 cubic meters, a space larger than Big Ben, excavated mostly by hand, with neither building permits nor technical expertise. They had decorated these “Temples of Humankind” with a rainbow of wall paintings, Tiffany stained glass, and mosaics. Endless halls snaked around the innards of the mountain, lit with candles and reeking of incense and paint.
More here.