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

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

This little museum is making sure that the art and history of the graffiti sticker is not scraped from history.

Floating swimming pool within a moored vessel.

Someone loved this song enough to carve all of its lyrics onto a tree trunk in a Berlin park.

Home to 10,000 medical specimens including the remains of Rudolf Virchow's extensive collection of pathological specimens.

Super-heavy Nazi architectural experiment.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

The most visited, and possibly most controversial, museum in Germany.

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

A collection of abandoned typographic signs from Berlin and beyond.

Art and a pun, all in one.

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

A slice of central Asia in the middle of Berlin.

Furniture tries to escape an abandoned building in San Francisco.

This one-block alleyway is stuffed with street art that is colorful, cultural, and intensely political.

One of few lasting examples of the brief octagon craze that developed into folly.

A pair of mutilated bronze octopuses slump at the base of the monument honoring California's admission to the U.S.

Recovered from the brink of extinction, at home in the Financial District.

The giant pair of sexy legs sticking out the window of this costume store have become its main draw.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

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

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.