This "mathematical tower" was an observatory, early skyscraper, and place to reflect on all of nature and the cosmos.

This beautiful Croatian fortress is haunted by legends of forbidden love.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

A miniature train-ride through Slovenia's largest cave system.

Deep underground, the rusting remains of a German water pumping station from World War II.

Island wonderland for communist autocrats.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

The costumes depict the Kurent, the star character of the annual Kurentovanje festival.

"World machine" built by an untrained Austrian farmer.

This open-air museum filled with 19th-century buildings offers a unique view of historic craftsmanship.

The NASA scientists behind Apollo 11 started out developing Nazi weapons at this abandoned German rocket factory.

Small museum dedicated to one of the founding fathers of modern astronautics.

This impressive collection of skulls and bones was gathered by an ex-zookeeper who took advantage of a pig plague.