Now we know where the Fortress of Solitude really is!

We just watched a cool show about an underground cave of giant crystals, to a lead and silver mine in northern Mexico. The crystals are huge, as big as telephone poles, made from gypsum, and they're a half million years old. It's so hot in the caves that the researchers can only spend half an hour in there at a time, while wearing all sorts of protective gear.


Here it is on YouTube.