This 30-foot pile of rocks may be the grave of a mythological Irish queen.

Certain traditions prevail on the least-visited island of the Aran Islands.

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

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

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

A former Latvian headquarters of the brutal KGB secret police is now open as a grim reminder of their atrocities.

Ancient mysterious ruts carved in the bedrock.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

The 3.8 billion-year-old rock proves that tectonic plates may have been shifting longer than we thought.

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

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

Nature took her revenge on the "Wickedest City in the World."

One of the largest ancient geoglyphs in the world is a tall desert god used for predicting the weather.

This "floating island" plateau sits 7,671 feet above the forest floor.

This everlasting lightning storm may be the world's largest generator of ozone.

An ancient stone fortress considered by many to be the eighth wonder of the world.

Hitler's bleak vision of relaxation still stands as a mostly abandoned 10,000-room resort complex.

Retirement home for giant obsolete machines.

These blingy, baubled skeletons lie in glass boxes inside a baroque Bavarian church.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

An intricate and amazing house built by architect Karl Junker.

The 1936 Summer Olympics site is a crumbling remnant of sportsmanship and a history its host country would like to forget.

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.