An underground city of salt.

Countless stories attempt to explain Poland's mysterious J-shaped trees.

A narrow opening between the mountains of the Amalfi Coast creates a scenic hidden beach.

This one-of-a-kind archeological site is home to strange prehistoric ruins, the original use of which is still a mystery.

The former home of an Italian artist is now a shrine to his ambitious works.

Ernest Hemingway was the first to sign this colorful wall covered in thousands of celebrity signatures.

An abandoned quarry hides an open-air gallery of huge sculptures, some made from the rubble of 9/11.

An unusual house built using an iso-elastic membrane.

The Cathedral of St. Ambrose has been hiding a special parishioner within its walls.

A quiet Sicilian village is home to a cafe that had an important role in "The Godfather."

This overgrown mountain village has been abandoned for nearly a century.

A tree that defies gravity grows in an ancient ruin.

Macabre symbols of death and mummies on display set the tone of this Italian purgatory church.

The world's first underwater farm is home to more than 700 plants.

One of the highest mountain passes in Europe has been ranked among the best driving roads in the world.

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

This medieval hilltop village was abandoned at the end of the 19th century, after existing for more than 500 years.

This church carved into the rocks is full of enchanting stone statues.

Amalfi's pre-industrial history is slowly being engulfed by the lush vegetation of the Ferriere Valley.

The naturally mummified body of a peasant girl saint.

A dreamlike medieval church dug into the tuff rock, with unusual carvings and possible traces of the Templar knights.

A unique form of erosion created an uncanny landscape of boulders perched atop slender columns of clay.

A slightly creepy gallery of plaster cast models in the same museum as Michelangelo's David.

The top of society once luxuriated in this world-class hotel, which continues to impress, even in ruin.