These cinderblock farmhouses were actually World War II radar stations in disguise.

Germany's Glienicke Bridge has a shady history of clandestine meetings, espionage, and spycraft.

Indents in the pavement are all that remain from a grisly death machine in Paris.

Today's aerospace industry can be traced back to one man and his gliders.

An extensive collection of ancient Egyptian artifacts and mummies.

The headquarters of a secretive order is also a beautifully-designed park.

A giant chess set, minus the psychedelic drug trip.

There has been an astronomical clock on this spot since the 14th century.

The site of the deadly Triangle Shirtwaist Factory Fire.

This shop and studio is dedicated to the art of the book, from letterpress to bookbinding.

Barça football fans might see the insignia hidden in a church window as a divine sign.

A once-secret library of Freemason history in Catalonia.

This store decorated with Japanese and underground pop culture items has been the centre of Barcelona alternative fashion scenes for more than a decade.

A forest of phallic offerings found in a quiet corner of a hotel car park.

On a river island north of Bangkok, a small bar helped lead a home-brewing rebellion.

A collection of venomous snakes and reptiles for the whole family to enjoy.

Part mural and part sculpture, this work of art sits in the middle of the Promenade, as if swimming in a river of asphalt towards the ocean.

Cavemen, elephants, and eagles greet passengers driving through the town's main intersection.

An ancient jungle temple carved into a rocky overhang of the Dane Soung Plateau.

This mysterious tower is said to enshrine a dormant seven-headed serpent that once protected Vientiane from destruction.

American bombs, morbid memorabilia, and graphic photographs tell the story of the CIA-led “Secret War” from the Pathet Lao perspective.

This Khmer temple is named after a young woman who sacrificed herself to protect the city from a disastrous deluge.

Thousands of crosses and markers for soldiers who lost their lives in Iraq and Afghanistan blanket a California hillside.

A Roman-inspired temple once controlled half of San Francisco's waters.