A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

A collection of abandoned typographic signs from Berlin and beyond.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

A surreal museum of extraordinary industrial objects.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

A wunderkammer of mysterious objects and stories.

Ruins of a German Castle on top of a towering stone pillar.

An eerie, derelict amusement park in Berlin.

Jumping-off point for a climb up Mt. Everest is the most dangerous airport in the world.

Last stop before the top of the highest peak in the world.

This secluded museum beats the drum for the preservation of Nepal's musical heritage.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

A blooming house of worship for the masses.

A startling, centuries-old subterranean marvel hides in plain sight.

Nestled among the artifacts of the National Crafts Museum, this hidden gem offers hard-to-find regional foods from all over India.

The classic Christmas carol was written at this Massachusetts tavern in 1850.

This massive World War II calculator hearkens back to the days when "computer" was a job title.

This plaque commemorates the call between Alexander Graham Bell and Thomas A. Watson.

A steampunk wonderland that preserves America's history of industrial innovation.

In 1958, an MIT fraternity pledge laid down on this bridge and instituted a new, unique unit of measurement.