This ancient cave is home to a museum, bar, and is filled with fluorescent minerals.

A tunnel with windows, so you don't miss out on the impressive views.

The fifth-longest natural arch in the world, and the longest outside China.

Once a menacing challenge for trailblazers, this trail is now the most scenic drive in Utah.

Come for the speed, leave in love with the desert.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

Home to the deepest rift anywhere on Earth.

A cemetery housing wild west legends in South Dakota.

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

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

The ghost town that ended up on Ebay.

Version of the French Riviera destroyed by the sea.

This abandoned Navy base was transformed into an off-grid alternative living community for thousands of people.

The smallest post office in the United States is no bigger than a broom closet.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

The concrete shell of an industry giant remains as a playground for graffiti artists, auto scrappers, and paintball warriors.

One man's attempt to create an artistic wonder on a run-down block in Detroit.

A Beaux-Arts triumph set to become Ford's innovation campus

The place where Samuel "Slater the Traitor" brought the Industrial Revolution to America.

Off a hiking trail in Rhode Island stands a picturesque memorial to a long-forgotten war.

This lighthouse was witness to the end of WWII hostilities and now collects creepy cairns.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.