The hidden offices underneath Memorial Bridge have been locked up since 1976.

The purported world's shortest international bridge connects a homeowner in Canada to his backyard in New York.

An ancient city exhumed from the depths of the ocean.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

Someone really, really wanted to save this fast-food icon from demolition.

In the 1940s, Italian architect Mario Cavallè built a dozen of these round homes in northern Milan.

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

A deeply beautiful 15th-century stepwell with a tragic story.

The most isolated mailbox in America lets desert travelers record their passing.

Once a safe haven for locals engaged in blood feuds, this 400-year-old fortified tower is now a museum showing what life was like for those lying in wait within its walls.

A forsaken wonder in the middle of the East Side neighborhood.

Eyam took steps to quarantine themselves and keep the plague from spreading.

This once-popular otherworldly landscape was formed by one of the largest volcanic eruptions in history.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

Made famous by 'Star Wars,' these troglodyte homes face an uncertain future.

A painfully obvious spy house sits right across the street from the Russian Embassy.

A secret fresh water spring for animals and humans alike hidden along the most famous road in the United States.

An eerie, derelict amusement park in Berlin.

This otherwise innocuous bodega was once the headquarters of the most feared assassin's guild in American history.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

This supermarket offers shoppers a window into the past alongside their groceries.

This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

The sunken structure looks like the victim of a catastrophic flood.