Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Eons old volcanic activity created one of the most stunning rock formations in the United States.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

Finale of "William Tell Overture" can be heard as drivers pass over grooves in the road.

An unfortunate geological resemblance to Satan has labeled this Pasadena gorge as a passage to the underworld.

A castle that was built stone by stone by an eccentric journalist.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

Panorama exhibition hall in old silent theater with a beautiful backyard garden.

A psychedelic labyrinth on the San Francisco bay.

A strange house built only at night, with rumored mystic inspiration.

America's most famous piece of self-built architecture.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

The mayor made the declaration in 2004.

The Largest Little Museum in the Northwest.

One of the coolest murals in Minneapolis.

An abandoned bus station transformed into a museum dedicated to the history of Greyhound Lines, in the place where it all began.

This Minnesota town celebrated the state's 100-year anniversary by creating a massive ode to nature's smartest bird.

A Borgesian work of art that may blur the line between fiction and reality a little too convincingly.

A whimsical sensor instrument for Minneapolitans to play on their walks to work.

14th century Norse artifacts in Northwestern Minnesota could have proved a Viking landing before Columbus.

This massive roadside mascot was the first version of the giant to illustrate his butt.

The Midwest's reigning king of surplus stores is full of nothing you need and everything you want.

Enter the Forest of the Elves.