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

An Orthodox church built by the Royal Family for the Russian community exiled to the French Riviera.

This massive blockhead sculpture hides an entire library.

Dedicated to the art of hunting, with juxtapositions of contemporary art.

A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

Mysterious lost empire of the Silk Road.

Modest by day, illuminated majestically at sunset.

An extraordinary "City of Caves" carved from solid stone.

305 homemade stone stairs wind their way up the Hamilton escarpment.

On the top floor of an upscale department store stands a lavish restaurant housed in a replica of a luxury French dining car.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

Beautiful stained glass depictions of the history of human flight fill this surprising chapel.

Only gap in the 30,000-mile span of roads called the Pan-American Highway.

A magical world of elves and fairies tucked amongst the trees in Colombia.

Enchanting cave with a river crashing through the roof.

An explosion of natural color known as "the river that ran away from paradise."

Unparalleled stargazing, one of Colombia's best observatories, and a swimming pool can all be found in the middle of this ancient tropical forest.

Storied crypts fill the most famous cemetery in Colombia.

Puffin enthusiasts flock to Europe's largest seabird cliff, which over one million birds call home.

A giant concrete orb in far north Iceland marks the ever-shifting boundary.

Three million year old fossils are exposed for all to see on this Icelandic shore.

This rusting remnant of the local herring industry is being given a second life.

This collection of unique liquids allows visitors to wander the waters of Iceland's glaciers.

Every summer local children form "pysja patrols" to save young birds that have wandered from their nests.