Perhaps the most spectacular grotto along the Algarve coastline.

Metro station with a claim to rock n' roll fame.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

Berlin's old airport.

This water-tower-turned-high-end-apartment building was once the site of an early Nazi concentration camp.

Resting in the middle of an Austrian river, this sci-fi "island" lets people cross in neon style.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

Climb inside an iron crystal magnified 165 billion times its normal size.

Brussels' favorite peeing boy has a sister.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Cold war icon and onetime "hole" in the iron curtain.

The prototype for all Nazi concentration camps.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

Artifacts and memories from the Vietnam war, located in a place that experienced it first hand.

A Surreal flight of architectural fancy in Vietnam's Central Highlands.

One of Vietnam's most iconic landmarks was built by Japanese traders and is now in danger of sinking.

The world's most important buildings shrunk to a tiny size.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This one-time health resort was used by aristocrats around the world.

A miniature train-ride through Slovenia's largest cave system.

The "dragon babies" of southeastern Europe.

The world's oldest grape-producing vine has survived four centuries of turmoil and even has its own anthem.

Apparently, Hell has waterfalls in Slovenia.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.