Probably a natural formation, nothing to see here. BTW, gratuitous Hitler shortly after 8mins 10secs. https://xcancel.com/TheProjectUnity/status/2016117028835172720 >This was accomplished with stone tools and workers lowering down buckets of fresh air to the stone masons. Those roving bands of hunter gatherers sure had a lot of free time! https://cosmicktraveler.wordpress.com/the-khara-hora-shaft-in-russia-2/ >The Khara-Hora shaft is a deep, narrow, vertical shaft discovered in 2011 by Russian speleologist Arthur Zhemukhov in the North Caucasus, within the Kabardino-Balkaria Republic of the Russian Federation. The shaft is 40 meters deep and constructed with large, precisely fitted megalithic stone blocks. The purpose of the Khara-Hora shaft remains a subject of speculation, as no conclusive evidence has been established through rigorous scientific study. Some theories suggest that it could be a remnant of a prehistoric civilization, a temple, a tomb, or an industrial complex. Others propose that it might be the subterranean section of a pyramid that once stood above the mountain, now long eroded.