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

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

A surreal museum of extraordinary industrial objects.

An old department store turned Nazi prison turned artist commune.

This classic restaurant features a gorgeous mirror-clad room.

When the rain falls, this drain system turns into a musical instrument.

This "floating railway" is one of the world's oldest monorail systems.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

Started as a kitchen garden, now the second largest botanical garden in the world.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

A spherical "micro-nation" in the heart of Vienna.

"World machine" built by an untrained Austrian farmer.

Where the lovelorn find a home for their sentimental keepsakes.

Budapest's Communist-era statues, banished to the suburbs.

A wellspring of natural Viagra found in Bosnia.

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

Artworks by loners, prisoners and the criminally insane.

In memory of The Blur Building, the temporary exhibition pavilion of vaporous nothingness.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

A German apartment building hosting as many trees as human occupants.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

Notorious artist squat renovated into legal studios.

Stroll through retro Paris while shopping for old postcards and discarded doll heads.

Paris' linguistic guide to the international language of, yes, love.