An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

Most-visited and most-photographed slot canyon in the American Southwest.

Rippling sand dunes frozen in the Arizona rock.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

Underneath downtown Lincoln resides a network of caves that was also the city's first brewery.

Storage units with a wartime past.

Other-worldly rock formations and ancient fossils abound in this unique stretch of Nebraska badlands.

A Texas-sized particle collider that was abandoned due to its Texas-sized budget.

This hollowed salt dome is the largest oil storage facility in the world, hoarding 250 million barrels of crude oil.

Home to an endangered salamander, a full moon celebration, and a large spring-fed outdoor swimming pool.

A free, canine-friendly alternative watering hole near the more famous Barton Springs.

The only nuclear weapon assembly and disassembly plant in the U.S.

A tribute to the little-known group of women who were the first ever to fly aircraft in the U.S. military.

Two massive and unstable sinkholes are yearning to unite, and their consummation could be catastrophic.

The 19th-century ruins hide deep in an overgrown forest.

The peaceful space is adorned by paintings by the famed abstract artist Mark Rothko.

The highest point in Texas is capped by a big silver pyramid.

Minimalist modern art on a repurposed military base in rural Texas.

These half-buried combine harvesters just off Route 66 are an homage to the Cadillac Ranch.

A spring-fed pool so deep it's used for scuba diving as well as swimming.

This beautiful grotto is one of those places where you can't believe you're just outside Austin.

Mysterious glowing orbs float through the desert night.

A 90-year-old underground water reservoir offers a more industrial kind of tranquility.