A 140-year-old castle with underground caves hidden in San Francisco.

A huge musical instrument played by the ocean.

A psychedelic labyrinth on the San Francisco bay.

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

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

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

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

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

A brass plaque dedicated to a convicted cannibal hangs in the National Press Club, and that's not even the craziest part of the story.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

A wondrous old library overlooking the nation's capital.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.