The world's largest single-aperture telescope resides in the Canary Islands.

A 19th-century mansion houses the largest collection of gin in the European Union.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

A temple to modernity, tucked away amid Barcelona's more well known museums.

A once-secret library of Freemason history in Catalonia.

The fantastic architectural models of a French traveler.

An art world insider finds himself battling for his artistic home.

Strange secondhand shop showcasing taxidermy and oddies

A lecture hall sink once used by Einstein and other noted physicists is now regarded as a strange science relic.

An ingenious Dutch land art project uses grass ridges to cut airport noise pollution in half.

A Portuguese Jewish cemetery filled with stunning grave monuments that date back to 1614.

This subterranean studio is filled with fascinating kinetic art.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

The spectacular history of spectacles on display.

The largest collection of handbags in the world, the oldest of which were used to carry Bibles, primarily by men.

Cat art as far as the eye can see.

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

Super-heavy Nazi architectural experiment.

This World War II bunker now survives as a documentation of the Nazi regime and war crimes.

Hidden beneath a restaurant, underground tunnels tell the story of Malta’s tragic role in World War II.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

This classic restaurant features a gorgeous mirror-clad room.

Named after a militant urban guerilla, this famous former squat is a graffiti-covered stronghold of leftist culture.

In Portugal, a secluded stretch of untouched natural beauty hides at the bottom of a steep hill.