A mile-long navigable cave adorned with stalactites and stalagmites reaching up to 65 feet tall.

A curious little museum dedicated to the furry feline in the cat haven that is Old Town Kotor.

Gargoyle head that brings good luck.

A saintly relic hidden in a Prague church basement.

This stunning iron gate designed by Modernist architect Antoni Gaudí is filled with mythic symbolism.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

This courtly monument celebrates an influential comedian who turned taking the piss out of the powers-that-be into an art.

The house where the writer spent his formative years.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

An 80-year-old plane tree is devouring an iron bench at Ireland's oldest law school.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.

Perhaps the oldest vine in North America, this sprawling plant helps make a sweet wine.

This abandoned amusement park was built on a site with a dark history.

A modern temple with an ancient philosophy.

Limestone outcrop decorated with a large laser engraving of the Buddha.

An enormous dragon scales the walls of this 17-story temple.

A limestone wonderland of water and subterranean secrets.

A white Buddhist temple with a golden restroom.

Stunning wetlands ablaze with pink lotus flowers.

A three-table eatery sits inside the home-kitchen of a seafood virtuoso in Bangkok's Chinatown.