Ancient cave tombs known as the "houses of fairies."

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

The world's tallest shot tower—maybe.

This ancient Chinese observatory still contains early astronomy technology.

The most famous location in China was home to whole dynasties worth of imperial rulers.

A massive volcanic plug is now a protected area that hosts a number of bird species.

The most powerful waterfall in all of Europe.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

A shrine built to combat the bad karma of a commercial venture.

These ruins of a pre-Columbian cliff village are among the most beautiful and well preserved in New Mexico.

Her final resting place was intended to be modest and private, but the power of her popularity continues to draw visitors.

Hundreds of dwarf beeches create an unusual, haunting forest in the north of France.

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

A rare chance to get up close and personal with a 13-mile ribbon of ice near downtown Juneau.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

Five candy-colored villages on the Italian Riviera.

A bright little alley in La Boca is a part of tango history.

The titular "little arch" near this Italian resort is one of the most popular diving spots in the country.

Self-mutilation in the name of beauty.

A focal point of the Cuban government, this city square features one of the most iconic images in the country.

Sitting in the basement of a castle, the largest wine barrel in the world is bigger than most apartments.