This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

This singular Irish dolmen is more Frank Lloyd Wright than upright stonehenge.

A hugely vast Irish landscape of barren rock that stretches for miles.

The ruins of an 800-year-old monastery boasts the tallest round tower in Ireland.

The oldest inn in Kilkenny was established by the first convicted witch in Ireland.

The ancient tomb acts as a calendar that keeps perfect time.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

An ancient neolithic tomb that only sees the sun twice a year.

This one has sailed five times as far as Sir Francis Drake's famous ship.

Catacombs turned marketplace.

A cluttered and astounding collection of antiquities and curiosities.

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

A colorful piece of contemporary art cheerfully clashes with Lyon's historical architecture.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

Hundreds of prehistoric stones, arranged in perfect lines in a French field.

A tiled, multi-level garden of survival in Lyon.

An art world insider finds himself battling for his artistic home.

For hundreds of years, automatons moving to metallic music have been marking the passage of time.

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

These quaint French houses dangle precariously over a precipice.

Massive puppet-automaton machines created by French artist collective Machines de l’Ile.

Monsters and miniatures are held in equal esteem at this wondrous museum.

Hundreds of hidden passageways weave through the old quarters of Lyon.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.