San Francisco Bay's ghost town.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

What happens here stays here – unless it affects the whole world.

Once a bustling fishing port, this semi-ghost town is now more than 90 miles away from the shore.

Planned as the world’s first zero-carbon city, it had lofty ideals—but is only 5 percent completed and aiming for 50 percent carbon-neutral.

An abandoned early-20th-century boomtown sits within the Calico Rock city limits.

The remains of diamond fever taken over by the desert.

Shoot for par over the bodies of the dead on this cemetery-cum-golf course.

Semi-recognized center of the world, with many oddities.

This concrete ship has had four careers - World War I tanker, floating amusement park, fishing pier, and artificial reef.

Where there's quartz, there must be gold. Thus is the story of the mines of Julian, and the titillating times of the Gold Rush.

Graffiti-covered ruins that were once part of a farm owned by a mental hospital.

This crescent-shaped sliver of sand is a magical haven for a herd of feral horses.

Vietnam's feral abandoned water park offers access to a post-apocalyptic funscape, now with fewer crocodiles.

A toxic ghost town sitting atop a massive coal fire.

The mummified relic of St. Catherine sits forever on a golden throne.

A funhouse dummy that turned out to be a real life mummy, Elmer McCurdy is an urban legend come true.

It might not be as impossible to reach as its name would imply, but just about.

An abandoned factory along the Mississippi coated by a giant mural.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

In the heart of Brigham Young's promised land sits a festering plot of industrial ruin that has been claimed by society's outcasts.

The remains of a Canadian train crash are now mouldering beneath layers of rust and graffiti.

The remains of this early 20th century refinery loom on a mountainside like a graffiti-covered fortress.

This once luxurious Catskills resort is now a haunting ruin.