Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

The world's most famous cheese caves.

A giant bug impaled on a 75-foot-tall needle.

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

Fortified medieval tower house with lovely roof garden.

A set of ancient drawings in the desert of Peru that are so massive, many of them can only be fully seen from the sky.

Flamboyant architecture from the turn of 20th century.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

From Tintin to the Smurfs, Europe's greatest graphic icons are celebrated in a grand Art Noveau gallery.

A stunning cemetery famous for its extraordinarily delicate & lifelike mourning sculptures.

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 old and harbors many surprises.

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