This frog-themed restaurant was frequented by Picasso, Saint-Exupéry, and more.

Once a 19th-century brasserie, this McDonald's exterior celebrates Alsatian design and the "King of Beer."

Notorious artist squat renovated into legal studios.

Abandoned railway line circling the city of Paris.

This Czech military museum is home to pink tank that was once a symbol of art and political rebellion.

The mystery of the Putim Ossuary involves a tricorn hat.

A controversial artwork draws attention to the dark history of Prague's "Suicide Bridge."

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

Underneath the city that invented pilsners are a series of historic tunnels that have been storing beer for centuries.

This network of conjoined cellars was riddled with traps and supposedly allowed the townspeople to pretend their homes were deserted.

Mysterious painted skulls in Moravia.

Enormous sandstone towers loom within a Czech forest.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

Europe's second largest ossuary wasn't discovered until 2001.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A church of bones, decorated with 40,000 human skeletons.

The 1936 Summer Olympics site is a crumbling remnant of sportsmanship and a history its host country would like to forget.

A medieval gate once used as a prison and how home to a city museum.

A plaque on the side of a building is a small tribute to the woman who invented an iconic Berlin fast food.

Learn the incredible story of how an unassuming spa town was transformed into one of the world’s largest uranium mining sites.

This impressive castle looms over small German town.

This ornate Weser Renaissance house was also the home of an infamous witch hunter.

This Late Gothic building that once housed Erasmus is now known as the filming location of "Suspiria."