Northern Ireland's Brobdingnagian stepping stones.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

Naturally formed rock city in Poland.

A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

While this monument tile is shrouded in mystery it also marks the end of the longest ever human chain.

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

A museum glorifying the life of Stalin, located in the city of his birth.

Ancient rock-hewn town that witnessed key events of Georgian history.

The charmingly disheveled clock tower of Tbilisi's puppet theater.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

Venice's island of the dead.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Go inside to really appreciate this 500-year-old technological masterpiece.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Eighty million natural history specimens call this gargantuan museum home.

Scattered throughout London are ancient remnants of the city's former bounding wall.

An unusual round church in London with a Templar past.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.