This spire on an Austrian mountain is wrapped around a long spiral slide and has the world's tallest wooden observation deck.

A giant glider—designed by the father of the Rubik's Cube's designer—now soars within a shopping mall.

The largest statue of this convex, homogeneous object with just one stable and one unstable equilibrium point.

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

Street artists transformed an abandoned air vent into the beloved Star Wars robot.

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

What looks like a crashed Zeppelin is actually a bright, airy reading room perched atop a modern museum.

The risqué mixed-media sculptures are supposedly a metaphor for Czech politics.

A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

A mocking tribute to the past and modern leadership of Prague.

This doorless 20th-century elevator doesn't stop or slow down.

One of the famous Czech artist's lesser-known Prague installations appears to be a glowing fetus affixed to a drainpipe.

This automated sculpture of two men peeing will spell out text messages with their micturition.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

What looks like a suicide in progress is actually a statue of Sigmund Freud.

A Jenga-style cylindrical tower of books that appears to go on forever.

Macabre astrological automaton clock dating to the late 1400s.

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

This legendary giant, born from vegetables, terrorized townspeople and cheated local children in games.

The legendary giant's severed hand sits on Antwerp's popular shopping street.

The world’s first statue of the late Apple co-founder.

A two-way chairlift system between Zugliget and the highest point in the city.