An urban laboratory.

This rural island is home to the ghost town of what used to be the world’s biggest salt mine.

Hidden in the hills of Western Pennsylvania lies one of the best-kept ghost towns in America that you can legally visit.

A ghost town that was wiped out by a flood in 1940.

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

Two geoglyphs that are truly unique to North America.

A set of ancient drawings in the desert of Peru that are so massive, many of them can only be fully seen from the sky.

Ancient human, animal, and geometric figures drawn in the earth.

Mine your own precious stones.

This pristine World War II airfield gives a comprehensive look at atomic development and aviation history.

These petroglyphs created by ancient Arizonians have withstood centuries of exposure to the elements.

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

A cave's rare beauty held a cavernous secret hidden underground.

Out of a desire to feed hungry soldiers, a franchise-altering idea was born.

This fast-food outlet is the only space and UFO-themed McDonalds in the world.

A blacklight journey through a celestial art exhibit.

A museum dedicated to the alleged Roswell Incident.

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

Explore a misty river canyon from a metal bridge system.

The former home of the army detachment that captured Geronimo.

A stone pillar commemorates the surrender of the extraordinary Apache leader.

One of the largest open-pit copper mining operations in the entire country.

Thousands of Mexican Free-Tailed Bats soar around an abandoned storm drain at sunset each summer.

Open since 1938, this diner has kept its fountain, malt machine, and all the gum that greasers left beneath its counter.