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

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

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.

Breathtaking and huge 430 year old maps of Italy.

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

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The yawning maw of this pagan visage is said to bite off the hands of liars.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

An abstract monument to a symphonic composer.

A subterranean house of worship carved right out of the bedrock.

This insurance company building reminds customers that witches, bears, and gnomes are out there, best be insured.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

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

This Polish cave has housed a dragon, a brothel, and an enduring legend.

Real bones which are said to have belonged to a Polish dragon.

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

Men in rubber-soled boots serve as your "brakes" on this toboggan ride Hemingway described as "exhilarating."

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

One of the largest Roman settlements in Portugal.

Ancient burial grounds of the wealthy.