Have you ever heard the one about the guy who literally lived under a rock in the Californian desert, where legendary flying saucer conventions were held in the 1950s? It’s one of those weird stories that a friend told me at a dinner party, which I of course Googled as soon as I could leave the table. But all I found was a few unsensational pictures of a big old lonely rock sitting in the middle of the Mojave desert– no sign of an entrance to an underground home or that any UFO conventions had ever taken place there. And then by chance today, during my weekly routine fish of the LIFE archives, I stumbled upon a photo series simply titled, “Flying Saucer Convention, 1957“.

No location or further information other than the photographer’s name, Ralph Crane, was given, but a quick comparison of the shape of the giant rock in the recent and old photos, and I knew this was it, I had rediscovered my unfinished story.

Better than I could have imagined, these fantastic black & white photographs extensively document the convention, from the quirky attendees and their campsites, the UFO memorabilia for sale, the buzzing scene that once surrounded this now lonesome boulder and best of all, a look inside the secret home that once lay beneath the giant rock…

But now I think it’s finally time I got around to telling you the story behind this bizarre underground rock home and how it got there– and it’s a pretty crazy story. We go back to the 1930s, when an eccentric German immigrant called Frank Critzer dug out this subterranean home for himself under the giant rock. He lived there alone, isolated from society with nothing but a radio antenna he set up on top of the rock to stay connected with the outside world.

I also tracked down this photo of Frank in his original rock house– via Labyrinthina.com

But get this– in 1942, during a showdown with police who came to investigate rumours that he was in fact a Nazi spy, Frank died from a self-detonated dynamite explosion in his own bunker. Locals had reported strange behaviour, several incidents of Frank threatening trespassers with a shotgun and suspicion that he was a spy because of his radio antenna. It turns out, he was just a radio enthusiast who wanted to be left alone in the desert.

After his death, Frank’s only friend, a former aircraft inspector named George Van Tassel, became the giant rock’s new tenant in 1947. The seven-story high rock had originally been sacred to local native Americans for centuries. This spiritual connection suited George quite well, because in addition to being an aviator, he also liked to dabble in the telepathic channeling of alien life. As you do.

In a few short years, George went from living a simple existence with his family in the rooms Frank Critzer had dug out under the Giant Rock, to building his own restaurant on the site, a small airstrip, and an extra-terrestrial research centre which would play host to his annual Giant Rock Spacecraft Convention, attracting more than 11,000 people at its peak.

Fellow aviation enthusiast, Howard Hughes is even said to have dropped by the air strip’s restaurant for a slice of pie.

Tassel’s onsite research centre, nicknamed “the Integratron“, was believed by many to have some pretty special powers– including ‘anti-gravitational and time traveling capabilities provided by extra-terrestrial life on Venus‘. For nearly 20 years it became the dream pilgrimage of every UFO nut enthusiast in America…

Let’s take a look at some of that UFO desert street style … first, all those wonderful hats!

And the flying saucer accessories…

UFO’s aside however, this does look like quite the interesting little family camping trip, wouldn’t you agree?!

The dome-shaped “Integraton” structure still survives today in Landers, California, near the Giant Rock but not as a pilgrimage site for ufologists. After Tassel’s death in 1978 there were plans to turn it into a disco. Instead, the new owners turned it into an 0ff-beat tourist attraction offering “sound baths”, claiming it to be “the only all-wood, acoustically perfect sound chamber in the U.S.”

As for the rock, in the year 2000 it fractured in two when a large piece broke off, revealing its white interior granite. Since the 1920s, Native American priests had predicted that the future of the 21st century would be foretold upon its fracture. Most likely, it was just telling us that too many UFO tourists had been burning their campfires under the rock. Sadly, the exterior surface is now partially covered in graffiti.

Another story uncovered thanks to the LIFE archives.