Super-heavy Nazi architectural experiment.

It's always summer at the beach inside this former airship hangar.

The Habsburgs' royal collections of art and wonders.

Cold war icon and onetime "hole" in the iron curtain.

Berlin's oldest surviving academic architecture hosted decades of animal dissections.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Hundreds of prehistoric stones, arranged in perfect lines in a French field.

This whimsically named Vietnamese stream is closer to a walkway than a waterway.

Across the Pacific in a raft, a museum dedicated to Thor Heyerdahl's now legendary expedition.

Home to three historic ships from the age of Vikings.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

A marvel of Byzantine engineering under the streets of Istanbul.

Explore this massive series of 45 caves and over 51,000 sculptures carved from cliffsides in China.

A fifth-century temple improbably built into the side of a cliff.

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

This smaller cousin of the Forbidden City has gone from ancestral sacrifice to tourist's whispers.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

The oldest museum in Russia is home to a fascinating collection of nearly two million anthropological artifacts and anatomical curiosities.

At 8,000 feet, the world's highest tea estate draws visitors for both its products and its panoramic views.

A battle between nature and architecture in the Cambodian jungle.

A nightmare for the claustrophobic lies hidden in Southeast Asia.

A desert in southeast Asia, complete with a beautiful lake covered in lotus flowers.