A remote lava tube out on the high desert north of Fort Rock, big enough that a section of roof has collapsed to let daylight into the middle of it, and once stocked as a Cold War fallout shelter, the supplies were later removed. Getting there is a long washboard road with no services and no phone signal, which is half the point. PUBLIC (BLM), Lake County, Oregon.
Oregon
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Other places on the map within a couple of hours.
