400 million-year old limestone caverns nestled in the Ozarks served as shelter and a hideout for cultures throughout North American history.

One of the world's earliest skyscrapers.

The Old Courthouse takes visitors on a captivating trip through St. Louis' timeline.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

Less a museum than a bizarre fantasy world created by artists and engineers.

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

A rocky Irish outcropping with a history of wealth, conflict, and ruin.

Behemoth, cannon-like telescope operated by generations of Irish earls.

An Irish peat mine has become a stunning sculpture park.

The oldest pub in Ireland may also be the oldest surviving bar in the entire world.

Dublin's most modern, visually spectacular bridge is modeled after Ireland's national emblem.

The modern birthplace of Irish freedom.

The block of aged dairy is probably still edible after 2,300 years in a peat bog.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

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

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

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

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

A memorial to the beloved brown bear that served in the Polish army during World War II.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

A collection of modern and vintage pinball machines housed in the cellar of a 15th-century building.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.