There are more pictures at the link.
Indeed, the Italian government was not even aware of their existence until a few years ago.
But the 'Temples of Damanhur' are not the great legacy of some long-lost civilisation, they are the work of a 57-year-old former insurance broker from northern Italy who, inspired by a childhood vision, began digging into the rock.
That's how these things always start, isn't it?
In 1977, he selected a remote hillside where he felt the hard rock would sustain the structures he had in mind.
A house was built on the hillside and Falco moved in with several friends who shared his vision. Using hammers and picks, they began their dig to create the temples of Damanhur - named after the ancient subterranean Egyptian temple meaning City of Light - in August 1978.