Hollowed-out mountains are good for so many things. They can house strategic military bases. They can store toxic waste. And if you’re truly evil, you have the option of carving it into the shape of a skull, making it your secret headquarters, or periodically host kung-fu tournaments there. Or, you know, all three.

The Norwegians are hoping to use their hollowed-out mountains for the altruistic, though ominously named, Doomsday Vault. The vault will be a depository of seeds of all the known varieties of the world’s crops, just in case anything goes down. NASA, on the other hand, recently announced that they’ll be upping the speed on the whole hollowed-out-mountain game by harnessing the naturally occurring hollow lava tubes on the moon as a library. Information could be stored on computers housed in these lava tubes and sent by satellite. At least it’s good to know that if one day NORAD happens to unleash its missiles or a kung-fu tournament on Skull Island goes horribly awry, all our seeds and back issues of PopSci will be safe.

What would you do with a hollowed-out mountain? Let us know in the comments section below. Me, I’d make a gigantic bounce house. And host a kung-fu tournament. —Dan Smith