This 600-year-old home seems to defy physics.

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

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

Historic medieval fortified city in southwest France.

French commune at the heart of conspiracies.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

These 18th century gardens tell a rocky story of the son of Odysseus.

Tiny castle in the middle of the Rhine made you pay to pass.

The last bastion of Roman presence north of the Alps looms over a German town.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

A former ironworks that was the first UNESCO industrial site.

1898 German railroad depot museum with working engines, steam train excursions, and hands-on displays.

What once sat in the world’s spotlight is today a largely disused ghost complex.

Giant marble phalluses on the sacred island of antiquity.

Replicas of Apollo's leonine stone guard cats still line a sacred row in Greece.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

The cruel trial of a 13-year-old boy inspired the creation of this now abandoned reformatory.

A cannon designed to fire an atomic warhead.

Meet manatees face-to-face at this zoo for native species.

In Florida, these naughty monkeys live on their own mini-monkey Alcatraz.