You can set up all the 50in televisions and kegerators you want, but your "man cave" is never gonna be as cool as the real caves Mother Nature creates. Sure, there's no hi-def or Sunday Ticket, but there ARE miles of rock formations, underground pools, and marble pillars. Plus, when summer gets its hottest, is there a better place to cool off than in Earth's own basement, where you can spend the afternoon in all-natural A/C surrounded by stalactites and stalagmites? (Tip: stalactites hang down from the ceiling, very tightly. Stalagmites come up from the ground and might someday reach the top. So you look cool on your nature walk.)
What, you'd still rather have the kegerator and Sunday Ticket? Whatever, be quiet. That's not an option, as these are the 15 coolest natural caves in America.