Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

Space-age monument to an early 20th-century uprising.

The cross-shaped memorial is filled with kitschy tributes to the late pop star.

Not far from a popular beach, an unfinished, abandoned mansion for Bulgaria's last communist dictator.

This historic black and white monastery is one of Bulgaria's architectural jewels.

A striking symbol of the Bulgarian capital.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

A collection of art from Bulgaria's time as a communist state.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

This massive stone and steel monument remembers a century-old battle that cost thousands of lives and nearly destroyed the city.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

An abandoned saucer-shaped monument in the Bulgarian mountains.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

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

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

Tintin's creator is celebrated in an immersive museum that's an astounding work of modern art.

The vast chamber inside this abandoned cooling tower looks like something out of a sci-fi dystopia.

Dedicated to the American general whose reply to a German demand for surrender was simply "Nuts!"

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A musical instrument played by the sea.

Tourists often confuse this beautifully ornate former cigarette factory for a mosque.

An elevator into the Baltic Sea.

This 1960's Soviet submarine in Peenemünde Harbor claims to be the largest submarine museum in the world.

The NASA scientists behind Apollo 11 started out developing Nazi weapons at this abandoned German rocket factory.