Spain's stunning solar energy plant.

A 16th-century Andalusian palace.

The world's largest wooden structure.

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

A windswept necropolis carved into the rocks overlooks the "most Portuguese town in Portugal."

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

A majestic hotel for dreamers rises from the center of a fairytale wood.

Houses are tucked between, on, and underneath giant boulders.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

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

This 47-story "M" needed 20 years to be completed

Mysterious Spanish catacombs of unknown origins.

This giant urban staircase was built to keep the city's brave fighting men from getting waylaid in the red light district.

The highest point in Belgium is a staircase to nowhere.

Museum covers every step of the chocolate-making process, from cultivation to the finished product.

Somewhere there is a giant who can no longer poop, but now travelers can stay inside his anus.

Brussels' favorite peeing boy has a sister.

A little sculpture with a large wardrobe.

Three floors of musical instruments coming from all corners of the world and hundreds of years of musical history.

Cozy basement bar sports an inventory of over 2,000 beers.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

Climb inside an iron crystal magnified 165 billion times its normal size.

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.