In this century-old literary safehouse, print is alive and well.

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

An essential stop before plundering, BYO Cutlass.

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

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

Tiki luxury on Nob Hill.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

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

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

A psychedelic labyrinth on the San Francisco bay.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A huge musical instrument played by the ocean.

A luxuriant botanical garden below sea level.

The story of a Floridian city as told through an obscure sport for retirees.

The first custom-designed building to showcase the works of Dale Chihuly is a wonderland of glass and light.

This ancient sinkhole-turned-healing-pool is a treasure trove of archeological discoveries and may even be the Fountain of Youth.

An eclectic treasure trove of maritime marvels.

These crumbling foundations are all that remain of the once-stately 1840s manor that gave the town of Bradenton its name.