A Jenga-style cylindrical tower of books that appears to go on forever.

The largest ice cave in the world is thought to be the entrance to hell according to Austrian legend.

A whimsical bridge adorned with decorative dragons.

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.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

One of the newest mosques in a city filled with thousands.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

Ancient serpentine sacrifice holder that has stood the test of time.

Roman ruins top white travertine terraces formed by ancient hot springs.

A marvel of Byzantine engineering under the streets of Istanbul.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

This vast masterpiece of Moroccan architecture spreads across 20 acres.

Deliberately hidden for centuries, the magnificent Saadian Tombs were eventually uncovered in 1917.

The largest madrasa in Morocco once housed more than 900 students within its exquisite walls.

It took 40 years to build this Eden-like garden in Marrakech, later restored by Yves Saint-Laurent.

Fortune tellers, snake charmers, poets, and storytellers all gather on this historic square in Morocco.

Traditional Danish spot where the schnapps are flowing and the smørrebrød is loaded.

This pair of gilded girls atop an Art Deco building in Copenhagen were built to function as a weather indicator.

The world's first combination ski slope and power plant.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.