Native American burial mounds? Giant gopher dens? No one knows what created the Mima Mounds.

These caves are home to a small church and were used to age cheese.

A surviving remnant of the thick ice mass that once mantled most of Western Canada's mountains.

A beautiful waterfall and beach where precious stones are plentiful.

This museum started as a collection of Manhattan Projects and continues to add exhibits as they are declassified.

More than 21,000 images fill this overlooked gem of a prehistoric site.

This innocuous New Mexico storefront was once the secret jump-off spot for Manhattan Project scientists.

The most powerful laboratory radiation source in the world pulses with 1,000 times the electricity of a lightning bolt.

A house filled to the brim with oddities and curiosities.

Though strikingly beautiful, Seattle's other railway station is now largely forgotten.

A beautiful 1920s tower filled with local hidden gems.

A plaque at the lighthouse where Frederick Valentich made his last radio contact before he vanished without a trace.

Mine your own precious stones.

This Nevada lake holds its titular natural pyramid and, if the legends are true, a number of dangerous spirits.

Originally built as a promotional giveaway, this suburban house was designed to be an IRL version of the Simpson home.

Albuquerque found the perfect use for tumbleweeds at Christmastime.

This towering volcanic plug stands out among the dramatic formations that dot this otherworldly desert valley.

A burnt-out motel with priceless Native American artwork in the basement, redeveloped into apartments.

When life gave this firefighter a forest fire, he made a rough-hewn sculpture park using a chainsaw.

Some 2,000 carvings show this rare desert spring has been an oasis for travelers for over a thousand years.

Hundreds of drawings left by the land's previous inhabitants remain mysterious.

Tens of thousands of ancient rock carvings hidden in the heart of a French national park.

The other side is actually green.

A mysterious monument where a woman who records say never existed was burnt alive for being a witch.