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

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

A striking 12th-century-style castle built on the edge of a cliff.

Ruins of a German Castle on top of a towering stone pillar.

Walk inside a half mile long crevice right outside the town of Garmisch Partenkirchen.

The fairy tale castle of the "fairy-tale king."

This army of concretions is an unexplained geological phenomenon unlike anything else in the world.

Historic medieval fortified city in southwest France.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

A subterranean shelter remains intact under a busy Paris railway station.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A quaint medieval millhouse hovers surprisingly above the waters of the Seine.

This futuristic observatory at the top of the Pyrénées offers unrivaled views.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This set of three large, volcanic hot springs is a favorite haunt for intrepid divers.

The "dragon babies" of southeastern Europe.

One of the greatest collections of coins in the world is housed in the former mansion of an archeological pioneer.

The historic tower houses of this nearly abandoned Greek town have been compared to the spikes on an iguana's back.

This 13th-century monastery chiseled into the side of a mountain is equipped with a bridge that can be lifted to protect against raids.

This abandoned Greek island was the last active leper colony in Europe.

This 15th-century island fortress later served as home to the executioners no one wanted to live near.

This wrecked ghost ship has been rusting on a Greek beach since the 1980s.