The remains of the second-oldest zoo in Europe can be seen within these library gardens.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

This small and often-overlooked museum holds some of Spain's finest artistic treasures.

Five million people are laid to rest here, more than the population of Madrid itself.

A lush indoor jungle fills this bustling Madrid transportation hub.

Earth's rocky history has rarely glittered so brightly as it does in this Spanish museum.

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

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

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

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

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

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

A beautiful but toxic fountain of mercury.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

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

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.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

Stripes of human ashes cover a back lawn in the most sought-after burial grounds in Paris.

This demon atop the Notre-Dame de Paris looks utterly bored.

The final resting place of the "father of special effects."

The bones of two medieval royal lions were discovered at the historic fortress.

This intricately carved and hilariously huge bed was such a famous symbol both Shakespeare and Byron used it in their writing.