Countless stories attempt to explain Poland's mysterious J-shaped trees.

A surreal museum of extraordinary industrial objects.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

Explore the complex ecology of this multifaceted nature preserve by riverboat.

The home of the morbid art of corpse plastination is open for visitors to view the fascinating, but stomach-churning process.

A former imperial sea-fortress and Soviet prison.

The ruins of an Estonian prison are drowning in the quarry lake where the convicts were once forced to work.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

An 1814 castle that hosts an exhibit of "explorabilia".

An eccentric garden of sculptures crafted in India decorate an Irish green space dedicated to Alan Turing.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

One of Ireland's most infamous prisons for rebels including men, women and children.

The northernmost point in Denmark is a turbulent sandbar created by two clashing seas.

Opulence and fantasy collide in this royal chair which is supposedly made with unicorn horns.

Hotel designed by indie graphics artists.

A taxidermied stork with an arrow through its neck proved that birds migrate.

This colorful artistic feature atop a Danish art gallery allows visitors to stroll through a rainbow.

Collection of nearly 500 concrete figures sculpted by the late Veijo Rönkkönen.

Man-made mineral caves house massive bat colony.

Tombstones buried in overgrown grass mark the deceased occupants of this abandoned graveyard.

Experience park where visitors are told to expect the unexpected.

This historical theme park celebrates all things noodle.

Crypt mausoleum in cathedral's basement contains relics of third century Roman martyr, Saint Vibiana.

A one-of-a-kind collection of a unique medium.