This former insane asylum now holds a pathological anatomy museum.

A whimsical bridge adorned with decorative dragons.

This abandoned Slovenian military barracks has become a punky-political art squat.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

A 16th-century horror show built in a lovely Italian garden.

Thousands of well-dressed mummies below a monastery.

Two small chapels housed inside an ancient tree.

This network of tunnels housed an entire village for years, and even had a hall for screening movies.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

What if all public housing projects had been designed by "the Pygmalion of modern architecture," not only their prototype?

Even France's favorite aquatic son Jacques Cousteau, couldn't get to the bottom of it.

A public park off the beaten path with a beautiful waterfall and 13th century Cistercian abbey.

For a brief time in 1960s France, families could climb into a tiny submarine and be pulled along an underwater journey.

Longest canal tunnel in the world, abandoned in the 1960s.

"Drunken ship" sculpture memorializing the French poet in the city where he died.

A massive 1830s industrial site once known as Czechia's "Iron Heart" has been transformed into a playground of science, technology, and art.

A perfectly preserved hill village where the buildings are painted like white lace.

This huge metal monument is slowly being stripped to its concrete skeleton.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

A wonderfully strange collection of 500+ stuffed frogs doing people things.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

The only gulag ever to exist in socialist Yugoslavia.

A forgotten monument to Yugoslavian freedom.

The remains of a sunken military ship wreck visible through clear water.