Gliwice Radio Tower, likely the tallest wooden structure in the world.

A small granite monument marks where the borders of three countries meet.

The center of this Polish border town was so thoroughly wiped out in World War II that only the foundations remain.

The oldest wind turbine in Europe, constructed by a group of friends in 1932.

The two abandoned overpasses are among the largest bridges in Poland.

In the midst of a living monument to Soviet social engineering, Polish Catholics built this church by hand.

Deep in a Polish forest, this collection of Iron Age megaliths still holds onto many of its ancient secrets.

Warsaw's fantastically preserved gasworks...almost.

A hidden art gallery in an abandoned Warsaw fort.

For 200 years, people have flocked to this Polish town to experience the healing powers of salt.

An extensive network of secret tunnels was created for the Nazi project "Riese."

This small red school was where Germany signed their surrender during WWII.

A garden of massive sculptures sits in Jean Lindard's backyard.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

Explore an eerie, abandoned medieval citadel.

This impressive chasm is one of the longest natural underground cavities in the world.

The huge golden reliquary of a testicle-smashing saint.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

A precariously balanced goose-shaped boulder with a dark legend.

Historic medieval fortified city in southwest France.

A medieval church built into an ancient cave.

Green labyrinth formed by a karstic maze hidden in a preserved oak forest.

Every half hour, the flow of this unusual spring cycles between a rush of water and barely a trickle.

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