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

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

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

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

Tiki luxury on Nob Hill.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

Its buzzing collection honors vibrator history.

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

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

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

A psychedelic labyrinth on the San Francisco bay.

A huge musical instrument played by the ocean.

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

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

This "life-size" depiction of Mickey Mouse as a half-lobster is both whimsical and a bit creepy, standing guard over the Boston waterfront.

Dedicated to one of the darkest moments in Irish history, this memorial has faced its fair share of backlash.

A plaque marking the famous abolitionist's birthplace often overlooked by visitors to the nearby Charles Sumner House.

A centuries-old church stands as a testament to Boston's "father of architecture."

This headstone marks the grave of an 11-year-old boy killed during clashes in the streets over the boycotting of British goods.

This historic Boston building has gone from personal estate to porn theater and back again.

This area was once known for being a lawless haven for rough-and-tumble sailors, earning the maritime-themed nickname "the black sea."

An interesting decoration on this historic site, this weathervane comes with as many legends as it does questions.

Each August, one of the largest religious (and food) celebrations in the country is held in Boston.