Go inside to really appreciate this 500-year-old technological masterpiece.

The enigmatic sculpture hides above an escalator in a Milan metro station.

An exclusive waiting room built for the royal family in the 1920s is hidden in Milan’s central station.

The secret medieval communication system will whisk your words above the noise of the crowd.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

This Art Deco airport was once deemed “the air hub of the Americas.”

This outdoor gallery of graffiti-covered walls pays homage to the past, present, and possible future of street art.

Sweden's oldest animated sign is still lighting up the skyline today.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

Two stone columns flank the grand Venice square, but there were supposed to be three.

One of the world’s smallest bars, just 13 square feet, is brimming with speakeasy flair.

The largest outdoor art gallery in the Northwest United States.

When in Idaho, sleep in a giant potato.

A black cottonwood gets a second life as a home for books.

A mining town, now abandoned, was built in a canyon so narrow that the railroad ran right through the hotel lobby.

Jail from the 19th century that was built by inmates.

The oldest Methodist church in the United States has been spreading the good news for over two centuries.

A pair of stones embedded in an Edinburgh street memorialize one of the city's last public hangings.

At the right time of day, sunlight floods through the roof of this cave and illuminates the small pavilion hidden within.

What’s a sure fire way to end up in jail in New York in the 1920s? Peddling bad moonshine.

A strip of modern stores in historic buildings.

A strange and haunting monument of unknown origin in the historic Graceland Cemetery.