An 18th century wonder of the world, lost in WWII, re-created at the Catherine Palace.

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

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

The largest medieval water tank on the Iberian Peninsula is preserved beneath the Cáceres Museum.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

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

The world's largest wooden structure.

The Roman city was the birthplace of various emperors and is home to one of the empire's most impressive architectural feats.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

These "mermaids" that surround a plaza in Segovia are rather sphinx-like.

This influential Renaissance-era library was once the haunt of kings and monks.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

A lush indoor jungle fills this bustling Madrid transportation hub.

Commonly acknowledged as the only public monument to the Devil himself.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

An ancient Egyptian temple in the middle of Madrid, Spain.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Once a year, at exactly 11:11 a.m., this monument comes to life.

Hundreds of hidden passageways weave through the old quarters of Lyon.

Lyon's miniature version of the Eiffel Tower was built as a statement in support of French secularism.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

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