This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

One of the world's most complex timepieces.

The world's largest solar furnace uses 10,000 mirrors to concentrate the sun's rays to generate power.

A Turkish ghost town abandoned in a population exchange with Greece.

Hundreds of hidden passageways weave through the old quarters of Lyon.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world’s largest coastal brick fortresses.

The naturally mummified body of a peasant girl saint.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The footprint of a frustrated devil in Munich's Cathedral.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

A building so large that it has its own weather.

An ancient capital city that dates back 3,000 years and harbors many surprises.

Island ghost town detailing Flagler's folly in building the Overseas Railroad.

A circus legend leaves an unexpected endowment.

Ancient man-made caves underneath small town Belgium.

His music once banned in Communist Cuba, John Lennon is now immortalized in bronze by Castro, who considers Lennon a "fellow dreamer."

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

Theme park featuring miniature replicas of European monuments.

Op-art architecture designed for happiness.

"We Seceded Where Others Failed."

Legendary site where an evil bishop was devoured by rodents.

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

Da Vinci's equestrian statue, 500 years in the making.

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