This Arab fortress was once the largest citadel in Western Europe.

This French "sea of rocks" is packed with stunning rock formations and its own medieval castle.

This French chateau is home to the world’s largest private collection of fighter jets.

The largest underground church in Europe.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

This rusting remnant of the local herring industry is being given a second life.

The oldest (maybe) swimming pool in Iceland is a stunning oasis built into the side of a lush hill.

The old Niles Canyon Aqueduct in the San Francisco Bay Area is a bemusing and secret trail through nature for wayward travelers.

This park is home to California's first oil boomtown, with structures that have stood for more than a century.

This vintage car parts store is also a museum devoted to a squat little gem of automotive history.

A lawless town deep in Death Valley was famous for its riches and death rate.

The decaying adobe remains of an old homestead are just off the beaten path in Joshua Tree National Park.

An Old West film set seen in countless TV shows and movies is open for the public to explore.

Burping, gurgling geothermal mud pots by the Salton Sea.

Antiques by the Bay.

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.

This old mining town, deep in the California desert, has a year-round population of one.

The quiet canyon has a tumultuous history involving a doomsday cult.

A world-class observatory in the California desert.

Named after a bandit and the star of several Hollywood prehistoric landscapes, these sandstone formations are a historical part of the Los Angeles natural landscape.

A volcanic tunnel illuminated by natural skylights offers a shaded respite from the desert sun.

Lucha Libre (Mexican Wrestling) themed taco shop.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.