"World machine" built by an untrained Austrian farmer.

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

This series of underground chambers contains Europe's largest subterranean lake that is slowly drained each day.

The world's largest collection of intentionally useless inventions.

This museum promotes informed contraception by documenting its often secret past.

This Austrian museum celebrates the work of famous forgers and their inimitable imitations.

Artfully arranged bones of 5,800 Austrians.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

Macabre museum devoted to historical Viennese murders.

Part shoe store, part sociopolitical art gallery, part zoo.

Slum Settlement Filled With Mountains of Garbage.

A preserved oasis with traditional Andalusian-style architecture and beautiful views of the Nile.

In Egypt's expanding metro area, many of the neighbors are dead.

A massive work of modern art that appears to be a crop circle in the middle of the desert.

Devilish masks, handicrafts, and pieces of old buildings create a snapshot of life in a historic Alpine region.

This picturesque mansion has gone from opulent ruin to nature museum.

An unusual and beautiful form of mass transit serves the city's steepest neighborhoods.

Largest monument in Colombia depicts 14 lancers who drove back an army.

Two identical statues by Fernando Botero, one blown to pieces in a terrorist bombing, the other donated as a gift for peace.

Storied crypts fill the most famous cemetery in Colombia.

This whimsical home made entirely from clay is basically a giant piece of pottery.

Cathedral carved out of salt, located a mile below the earth's surface.

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

Colorful lights and mirror-like brine pools create trippy illusions within the historic mine.