The Curio

I think I’ve posted some of these pictures before, but I like this kind of thing.

Web Urbanist » 7 (More!) Underground Wonders of the World: Lost Caverns and Buried Cities:

“Humans burrow into the Earth out of anything from necessity to superstition, driven by coincidence or coerced by circumstance. Without further ado, here are seven more underground wonders of the world.”