Mile-long cave system near Great Smoky Mountains.

A once-groundbreaking power plant turned into a hotel and mini-museum of archeological and geological wonders.

Inside this striking glass building, visitors can see thousands of dinosaur fossils in the positions that nature deposited them more than 150 million years ago.

It's safe—and permitted—to walk across these twin natural sandstone arches.

A taste of Middle Earth, in the middle of the Bayou City.

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

Journey through various trails to discover a land before time along the Chazy Fossil Reef.

The remains of Abó, Gran Quivera, and Qurai are monuments to the long, complicated history of the Indigenous people of the Southwest.

Where you can hail your favorite fictional commanders-in-chief.

The Icelandic Sea Monster Museum explores the area's history of aquatic cryptid sightings.

The massive cave church of Cairo's Zabbaleen community is one of the largest Christian churches in the Middle East.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

This whimsical stacked cabin looks like something out of a children's book.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.