A monument to the love people have for their pets.

A Barbary Coast watering hole built into a Gold Rush shipwreck.

The remains of a ruined mansion memorialize the 1906 earthquake.

Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

A nondescript building that's been functioning as a speakeasy for nearly a century and a half.

A shop full of natural curiosities, carnivorous plants, and costumed taxidermied mice.

Visible below the waves are memorials to the city's Gold Rush dead.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

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

From Iggy Pop to David Bowie to Nick Cave, this regal music studio has served some of the all time greats.

An abandoned swimming pool decays on the outskirts of Berlin.

Blitzkrieg bop your way through Berlin's Ramones Museum.

The 1852 novel "Uncle Tom's Cabin" lends its name to a subway station, a street, and several shops on the edge of Berlin.

This concrete residential area doubles as an open-air gallery.

The original burial place of this preeminent 18th-century Jewish philosopher was razed by the Nazis.

The last remnants of a massive medieval wall that once encompassed the city of Berlin.

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

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

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

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

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

A slice of central Asia in the middle of Berlin.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.