Ecuador's largest Incan ruins show evidence of sophisticated irrigation and diplomacy among the ancient builders.

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

Berlin's old airport.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Furniture tries to escape an abandoned building in San Francisco.

At the base of the Golden Gate Bridge, a small sign basically begs for a high-five.

Depicting scenes of everyday life - and specific individuals - in Great Depression era San Francisco.

These subterranean storage areas hold emergency water reserves.

One of the oldest producers of hand-folded fortune cookies still uses its original secret recipe.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

A man-made island in scenic San Francisco Bay.

A monument to the love people have for their pets.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

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.

San Francisco's newly reopened hands-on science museum.

Tiki luxury on Nob Hill.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A winding path built in secret on the edge of the continent.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.