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

A beautiful but toxic fountain of mercury.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

A whimsical bridge adorned with decorative dragons.

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

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

The "dragon babies" of southeastern Europe.

This massive subterranean fissure is known as the "underground Grand Canyon."

A sinuous path among steep cliffs creates a stunning sight in southwestern Serbia.

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

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

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

This bone-filled cave got its name after they found 140 bear skeletons inside.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

A majestic hotel for dreamers rises from the center of a fairytale wood.

A small Portuguese cottage formed between boulders in the countryside.

One of the largest amphitheaters in Europe is a former Nazi gathering place that still stands today.

The world’s narrowest house makes for an awkward, four-foot-wide living space.

This man-made mound monument was built out of soil from all across the Polish empire.

This fairytale inspired, warped building houses restaurants, shops, and a radio station.

Naturally formed rock city in Poland.