This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

This WWII-era military installation once held an entire city within its walls - now, its walls are falling down.

While not recognized by Guinness, this chocolate waterfall is likely to be the world's largest.

Once the fastest ship from San Francisco to Tahiti, the Galilee now lays in pieces in three different cities.

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

Guns that have been defending San Francisco since 1904.

Art in the form of a winding, man made crack in stone.

The only visible piece of San Francisco's most famous shipwreck.

This concrete tangle of square pipes has stood as a proud thorn in the city's side since the '70s.

A man-made island in scenic San Francisco Bay.

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

An essential stop before plundering, BYO Cutlass.

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

A still functioning vaudeville carousel that has operated for over a century boasts a colorful menagerie and past.

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.

The tea room that pushed the boundaries of adorable straight into...we can't find the words.

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

Eighty million natural history specimens call this gargantuan museum home.

This luxury shopping lane has been protected by its own tiny police force for over a century.

Charles Babbage's proto-computer, painstakingly brought to life.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.