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.

Relics from as far back as the 16th century are on display in a city known for its playing card industry.

Sleep in a climate-controlled plastic bubble for the night.

The world's tallest bridge is also possibly the most elegant.

Five candy-colored villages on the Italian Riviera.

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

This unreal Portuguese palace looks as though it's made from a pile of different castles.

A formerly opulent Italian village is now a crumbling ghost town that no one really knows what to do with.

Now an entertainment complex, the Lingotto building was once an avant-garde auto factory with a test track on the roof.

These quaint French houses dangle precariously over a precipice.

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

The history of sea-faring refuse and disaster is on cramped display in this Netherlands folk museum.

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

This ghost town in Belgium will lose its street art when it ceases to exist.

A small Portuguese cottage formed between boulders in the countryside.

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

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

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

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

A stunning cemetery famous for its extraordinarily delicate & lifelike mourning sculptures.

Walk through living pictures and music in the Cathedral of Images.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.