The oldest farmer's market in America is so ancient it was approved by the King of England.

Eccentric concrete mansion and museum designed and built by hand from the inside out.

Historic medieval fortified city in southwest France.

Ancient paintings known as the "Sistine Chapel of Cave Art."

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Abandoned railway line circling the city of Paris.

The rusted remains of an ill-fated freighter lie just off the coast of South Manitou Island in Lake Michigan.

An angular maze of concrete in Grand Rapids acts both as public art and as a staircase for fish traveling upstream.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

At first glance, this area seems like just another city park, but the lush landscape hides a dark past.

A museum of co-operativism housed in the birthplace of the modern movement.

This dreamy street will transport you to wintertime in Victorian England.

This tiny watering hole claims to have the smallest bar counter in Europe.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

Dictionary Johnson’s favorite feline.

London's smallest police station is barely the size of a phone booth.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

Hidden beneath the streets of London is a secret subway that only carried mail.

A kaleidoscopic warehouse-maze of handmade neon signs.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

South Philadelphia is home to Keith Haring's only surviving in situ collaborative public mural.