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

Europe's largest natural bridge has a 19th century royal chateau built into its side.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

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

This one-time health resort was used by aristocrats around the world.

This massive subterranean fissure is known as the "underground Grand Canyon."

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

A serene desert oasis speckled with ancient artifacts.

These numerous Israeli caves were dug out over hundreds years for reasons ranging from hideouts to burial sites.

Floating swimming pool within a moored vessel.

A slice of central Asia in the middle of Berlin.

A trough of 700 strange bronze faces runs through a narrow alley in Ljubljana's old town.

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

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

A whimsical bridge adorned with decorative dragons.

A series of playful yellow penguins share a serious message about the environment.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

Tucked away in a Prague park, a statue beloved by romantics honors a poet so nice they buried him twice.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

The oldest garden in Prague, once part of an medieval orchard.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

This charming wooden church was disassembled and moved not once but twice before settling in this Prague garden.

A saintly relic hidden in a Prague church basement.