In a largely deserted ghost town, a little brick building recalls its history as a gold rush hub and haven for outlaws.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A clear blue swimming hole with hidden caves, still unexplored.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

The ruins of this Roman temple dominate the small city in southern Lazio.

This medieval mountain town is also known as the "Village of Streams."

A 2,000-year-old engineering wonder hides beneath an Italian town.

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

A cave in southern Italy adorned with thousand-year-old Biblical frescoes existed in obscurity until fairly recently.

This large, circular tomb is the final resting place of the first emperor of Rome.

One of the most well-preserved castles in Italy also contains a rare medieval example of a port fortification.

This ancient altar emerges from the thick forests to reveal the mysteries of Etruscan sacrificial rituals.

Deceased nuns were placed on stone chairs to decompose, while the surviving nuns prayed near the lifeless bodies.

The walls and streets of the ancient city are peppered with penises.

A small window on Via Piella offers a lovely and rare peek at Bologna's lost canals.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

A sulfuric hellscape in southern Italy.

A domed disco abandoned since the '70s now attracts artists and explorers under its unique roof.

The bomb-ravaged remains of of a colossal Neptune.

A massive natural rock arch gives the Tuscan mountain its own window to the sky.

This Italian dam is covered in salt-hungry goats who manage to scale its almost vertical face.