For centuries, humans have lived underground. Today, that ancient practice is under dire threat—even as cave life makes more ...

Billionaires are building ultra-luxury doomsday bunkers that rival five-star resorts with lavish amenities beneath the earth.

That gust of cool air is what led two National Park Service employees to stumble upon Crystal Cave while fishing at a nearby ...

Carved from stone over thousands of years, caves are nature’s underground masterpieces. Here’s the wild process that turns solid rock into surreal worlds—math errors and all.