This is again, an amazing well done work.
However: I can't really tell why this scares me so much. It gives me some kind of "claustrophobic anxiety" even though it's not showing a small space. But: It seems to be set inside a giant cave, perhaps underground (?), and that's not necessarily a save place.
I am reminded of the Roman city of Petra. If the people who lived there had been demon worshippers. Compare this picture: