This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

This historical theme park celebrates all things noodle.

A fantastic castle rumored to be the birthplace of King Arthur.

Pompeii's less famous neighbor is still revealing her secrets.

An antiquated German apothecary on Chicago's North Side.

A whimsical village of unique treehouses resides in a Washington forest.

After starting as a whimsical tourist attraction that eventually found its way to ruin, these renovated canals offer a lush and exotic locale on the Pacific Coast.

Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

A 70-foot-deep ice cave formed by lava from Mt. Fuji on the edge of Japan's "Suicide Forest." 

Stunning wetlands ablaze with pink lotus flowers.

The underground sanctuary of a mysterious ancient cult.

A swing to dangle you off the very edge.

A clear blue swimming hole with hidden caves, still unexplored.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Despite the ever pressing encroachment of urban sprawl this grand New Orleans manse still stands.

Renaissance villa and gardens complete with a tormented colossus.

Remnants of a Victorian garden feature sitting in public woodland.

The middle finger of modernity.

The restaurant keeps a hidden séance room on the second floor and reserves a table for the spirit of the former owner each night.

A very classy 1920s-era bar right in Grand Central Station.

Walk through Czech history in Prague's largest graveyard.

Rome's semi-secret peephole vista is also a former Crusader stronghold.