This ancient theater was once the home of fierce gladiatorial battles.

This recessed garden protects thousands of mountain plants by creating its own microclimates.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

The first green space constructed on an elevated viaduct.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

An eatery for UFO seekers on the Extraterrestrial Highway.

Mysterious meeting place for UFO hunters near Area 51.

In the middle of a remote desert town is a surprisingly opulent hotel.

This tiny cluster of abandoned buildings looks like the future of the ghost town - today!

Eastern zen meets Western grit in these four little trees growing out of a rock on Lake Tahoe’s Nevada shore.

This 18-foot-tall steel lotus is a meditation on ecological crisis that originally appeared at Burning Man.

These once-beautiful historic graveyards are set against the barren Virginia City hills.

An iconic 1960s theater with a Buckminster Fuller-style geodesic dome.

This beloved roadside attraction welcomes visitors with his signature neon smile.

Back in the day everyone who was anyone played this historic western theater.

The arch that celebrated the completion of the Lincoln and Victory highways.

Singing sand that stands as the final remains of an ancient lake.

A tree bears footwear on the loneliest road in America.

The current Eureka County Courthouse replaced an all-wooden structure that had previously been an ice-skating rink.