This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

This massive underground salt mine now holds a sci-fi theme park in its depths.

Moss and stone turn this waterfall into an otherworldly liquid veil.

This war memorial holds the remains of around 20,000 World War I soldiers from both sides of the conflict.

This medieval castle was reconstructed by Carlo Scarpa.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

One of the world’s longest pedestrian suspension bridges.

This architectural beauty is the home to a personal collection of more than 600 examples of mechanical musical instruments.

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

The best place in the world to buy tinned fish.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

Dug as a secret royal escape route, the tunnel became a wartime bomb shelter and dumping ground for vintage cars.

Bohemian paradise covered in majestic forests.

Old cabin-like homes in a rural community untouched by time are known for their vibrant and colorful window shutters.

A gorgeous stone viaduct crosses over a bucolic valley.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

The world's first cruise ship-shaped hotel is perched atop a cliff.

A monument to the man who almost killed Hitler.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

Someone loved this song enough to carve all of its lyrics onto a tree trunk in a Berlin park.

This extensive collection covers thousands of years of Polish military history.