A retired military stronghold on the rolling green coast of Donegal.

This rare and ancient Christian relic is one of Ireland’s oldest freestanding stone crosses.

This World War II relic let Allied pilots know they were entering neutral airspace.

A massive Celtic cross secretly growing in an Irish forest.

You can see three Irish counties from this Neolithic hillside fort, once the seat of the Kingdom of Ailech.

It's said to be one of the most significant collections of contemporary Chinese art in the world.

Cockatoo Island is a Heritage-listed island in the middle of Sydney Harbour.

Come for the flowers, stay for the bats!

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

An existential riddle in the world's largest ancient castle.

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

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

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.

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

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

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

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

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

This artificial cave looks like something out of a fairytale.

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

Walk through Czech history in Prague's largest graveyard.

Macabre astrological automaton clock dating to the late 1400s.