it's extremely difficult to build waterproof subterranean buildings, especially if they're built into permafrost (which seems these days to be more like tempofr

it's extremely difficult to build waterproof subterranean buildings, especially if they're built into permafrost (which seems these days to be more like tempofrost). this very long but fascinating video discusses it: https://www.youtube.com/watch?v=nphxoUxSvgY https://www.youtube.com/watch?v=nphxoUxSvgY