These mouldering mansion ruins remember a time when the Catskills were nothing but luxury.

This ruined castle perched atop a rocky peak is a great place for a hike.

Underneath the city that invented pilsners are a series of historic tunnels that have been storing beer for centuries.

This fairytale medieval church in Poland originally spent centuries in Norway.

This fortress was designed to prevent a Nazi invasion but was never used.

A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

Tall columns of volcanic basalt make up this improbable-seeming rock formation.

Europe's largest natural bridge has a 19th century royal chateau built into its side.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

A slice of central Asia in the middle of Berlin.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

Started as a kitchen garden, now the second largest botanical garden in the world.

A 12th-century fortress containing some of Berlin's oldest buildings.

The natural mummy of the less than chivalrous Knight Kahlbutz.

Executed in 1401, Exhumed in 1878, Stolen in 2010.

The small alleys in Lübeck's Old Town are a result of medieval urban sprawl.

Tiring of digging out the door to this church for every service, it was eventually abandoned to the sands.

Remnants of the Nazis' occupation of Denmark linger along the sand.

Iron Age "bog person" preserved for over 2,300 years.

Nearly 40 miles and 1,000 years of limestone mines under Denmark.

This enormous aluminum figure in Denmark lying in a plunged position, echoes the global debate on canceled historical statues.

Discovered in a peat bog, these horned helms come from a thousand years before the Viking Age.

This old cement mine has been used as everything from a mushroom farm to a recording studio.