In the Samara region, not far from the city of Syzran, on the bank of the Volga there is an interesting underground object. Pervomayskiye bitumen adits. Bituminous limestone was mined in these adits, and at a small plant located nearby it was immediately processed into bitumen and asphalt. The development was carried out a long time ago, in the middle of the 18th century. In total, four systems have survived. Three of them are very small, due to collapses, most of the tunnels are filled up. And one system is quite large, with many passages. There are also local attractions - a small underground lake - in the main photo. There is a strange metal structure, probably left by the miners (photo 5).
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The tunnels have a constant temperature of about +7 degrees Celsius. Each spring flood completely floods the caves, so the humidity is high. But during the summer, some of the tunnels manage to dry out, although sticky mud remains in places. Bats also live here - unfortunately, I was unable to photograph them. They fly too fast, and I was unable to find a sleeping bat...
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This is what logging in looks like from the top of a cliff
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