One of Europe's largest supercomputers is housed inside of a disused chapel.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A sculpture park that takes the use of clay to a whole new level.

A 200-year-old collection of medical paraphernalia in a historic house.

A floating underwater hotel, created by a Swedish artist.

The deepest hole drilled in the name of science, where evidence of Precambrian life was found.

A collection of cafes and shops all crafted from recycled storage containers.

Where better to stay the night than inside a trio of ancient Chinese deities representing "the good life."

A complex and beautiful system of rice terraces covers a million acres over the mountains.

A replica of the home of a famous fictional troll family.

See just what life was like in a 19th-century prospecting town.

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

This abandoned, turn-of-the-century astronomy hub is now the subject of more photographs than it ever took.

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

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

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

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

An architect transformed this abandoned cement factory into his castle-like workshop.

A lush indoor jungle fills this bustling Madrid transportation hub.

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.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

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