A small but immensely extravagant palace built by the "Night King."

The fairy tale castle of the "fairy-tale king."

The walls of this medieval church are covered with perfectly preserved frescos, including a pristine example of the Dance of Death.

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

A whimsical bridge adorned with decorative dragons.

The "dragon babies" of southeastern Europe.

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

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

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

One of the most powerful religious centers in the Middle Ages, dubbed the founder of Western monasticism.

The opulent home that inspired Tintin's Marlinspike Hall and the adventures within.

From carts to cars, this leftover Roman bridge in France has managed to survive for centuries.

One of the largest ochre quarries in the world, hidden in a limestone landscape.

This bridge was constructed from the rubble of the infamous Bastille.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

The world's tallest bridge is also possibly the most elegant.

Historic medieval fortified city in southwest France.

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Op-art architecture designed for happiness.

The topiary maze at the Habsburg hunting lodge.

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.