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

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

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

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

The industrial monstrosity known as Bagger 258 is a colossal mining machine built in the DDR - but now left for dead in a German field.

It's always summer at the beach inside this former airship hangar.

Terrifying derelict military hospital once housed a recuperating Hitler.

The ruined remains of the airport Claus von Stauffenberg departed in his failed attempt to kill Adolf Hitler.

The music is over at the Ballhaus Riviera Ballroom, but the ballroom remains in haunting disrepair.

An abandoned horticulture institute gloomily presides over rows of derelict and vine-wrought greenhouses.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

A state-of-the-art medical facility from the Imperial era is now a derelict ruin.

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

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

A palatial sculpture park was built illegally and in secret by a self-taught artist over 36 years.

Countless grotesque faces stare out from this eerie Prague art wall.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

Two stunning 17th-century libraries and a cabinet of curiosities.

After a short 5 year run, this former major theme park sits in ruin.

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.

This beautiful natural train tunnel is said to grant the wishes of visiting lovebirds.