For years, people living in the Bow Valley and Kananaskis have spoken of a hidden, never completed nuclear shelter below the slope of Mount McGillivray.
The facility, inside the mountain outside Canmore, was part of a Cold War-era plan to keep important government records safe in the event of a disaster, up to and including a nuclear bomb.
But its construction, started in 1969, was never completed.
"I don't know why they stopped. I suspect it was the water, given the amount of moisture coming in," said local historian Rob Alexander. He wrote a detailed profile of the bunker for Highline Magazine in 2009.
"I think they got only one-third of the way through in construction," he said. A main tunnel goes more than 55 metres deep into the mountain, with another side tunnel, more than 40 metres deep itself, branching off just after the entrance.
It's dark, it's dank, it's cold.- Rob Alexander, Bow Valley historian
In a late 1960s advertisement, the company behind the bunker boasted it would provide "maximum protection against any form of destructive vice, from mildew to hydrogen bomb."
The intent was to provide a "vault storage area" to protect critical documentation and information in the event of some sort of catastrophic emergency.
"The businessmen responsible for the industries of a country must provide data storage areas which are completely protected," reads the bunker's promotional brochure, which is possibly the only publicly available document from the now defunct company behind its construction.
Rocky Mountain Vaults and Archives Ltd. was based in Calgary and boasted of its ability to keep documents safe within nearly 275 metres of limestone, with no "underground water" being anticipated.
Given the high level of moisture inside the cave on a visit in 2018, it's hard to believe any important documents would stay dry at all, let alone mildew-free.
"Inside it's dark, it's dank, it's cold," said Alexander.
"This would not have been useful at all. And the problem with limestone is there's cracks, it's fairly porous that way. So the moisture is all coming through," explained the local historian.
Intended to be fully survivable unit
According to the promotional brochure, the bunker was planned to be fully self-sufficient in the case of a disaster.
Emergency electricity, temperature controls, air exchanges and communications systems were all planned.
"So in the event of a catastrophe, whether it was a fire or a nuclear war they could seal it off and survive quite nicely down here," said Alexander.
Both a tourist and party destination
The empty vault caves often attract locals looking for a place to party, as abandoned beer cans and graffiti suggest. As well, tourists looking for an off-the-beaten-path spot to visit can be found on a regular basis between the hollowed-out walls underneath Mount McGillivray.
"I wasn't really expecting this to be honest with you, the size of it," said Chris Norman, visiting the cave-like tunnels around midday on a summer Friday afternoon. He and his wife Andie, both of Calgary, were looking for an unusual day trip and found information on the bunker through a Google search.
"Oh it was so weird. So spooky!" said Andie. "You can kind of hear the dripping and you're not sure if it's people or ghosts or something else so it's kind of ominous."
Despite his long-standing interest in the unfinished mountain opus of Rocky Mountain Vaults and Archives, Rob Alexander isn't sure the barren limestone walls deserve any legal historical status.
"It doesn't kind of hit that national scale compared to, say, the Diefenbunker which was finished and was used and you can visit it," said Alexander.
"I think [it's interesting] because it's unfinished and it is something of a minor relic in terms of Cold War history," said Alexander.
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With files from Caroline Wagner and Erin Collins