In the ongoing effort to establish a permanent lunar base where humans can live and work on the moon, scientists have discovered a possible game changer: a large underground cave. For decades ...

NASA has found a large hole on Mars. This hole might lead to underground caves. Scientists think these caves could hold alien ...

Whether you're drawn to geology, adventure, or simply the strange beauty of the underground, these seven caves are unforgettable stops that deserve a place on your U.S. travel map. Tucked beneath ...