Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.

This nondescript tunnel has been featured in a number of iconic movies, from “Roger Rabbit” to “Back to the Future.”

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

This historic recreationist school churns out warriors that may very well have had a fighting chance in Rome's pits of the day.

A forgotten "city of water" underneath the famous Trevi district.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Two monstrous faces loom over a village in Czechia.

Tall columns of volcanic basalt make up this improbable-seeming rock formation.

Straight out of a nightmare, barcode-faced babies climb up and down Prague's television tower.

A giant interactive periodic table with real samples of the elements.

A bus with a butt and biceps to put Olympic athletes to shame.

Microscopic scenes; some call it novelty, some call it art.

An Orwellian sculpture with eyeball cameras watches passersby.

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

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

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

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

The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

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

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.

The hidden lair of an alchemist rediscovered in a 2002 flood.

Countless grotesque faces stare out from this eerie Prague art wall.

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