Just a few miles from downtown Atlanta is a trail covered in a crazy collection of outsider art.

Mile-long cave system near Great Smoky Mountains.

Hiding behind a grocery store is a spectacular cavern carved as part of an old limestone quarry.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

A remarkable cabinet of curiosities in an art space in the center of Berlin.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

Once a path for Jewish funeral processions, this unassuming alleyway is rich in local lore.

Inside this Jewish cemetery is a memorial to soldiers who deserted the German army and were executed.

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

One of the oldest cemeteries in Germany was originally used for victims of a cholera epidemic.

Concerts, art, offices, and a café in what used to be Berlin's first crematorium.

This sprawling Jewish cemetery is one of the largest in Europe.

Metro station with a claim to rock n' roll fame.

One of the world's heaviest musical instruments towers within a popular urban park.

A traditional U-Bahn station in Berlin gets a string of rather untraditional benches.

The final resting place of many of Germany's most famous communists.

Cold war icon and onetime "hole" in the iron curtain.

Known simply as "The Hand," this famous public sculpture in Berlin was featured in a Depeche Mode music video.

Puppet theater and museum holding a collection of more than 300.

Named after a militant urban guerilla, this famous former squat is a graffiti-covered stronghold of leftist culture.

A restaurant and observation deck built in a unique broadcasting antenna.

Berlin's old airport.

Visitors can explore the role of mysticism throughout the ages inside this interactive museum of magic.

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