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

Mysterious 500-year-old tapestries depict a unicorn hunt.

Try not to get slimed in Tribeca.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Elevated freight railway turned wildly successful urban park.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.

The oldest operating apothecary in the US has treated everyone from Thomas Edison to Mark Twain.

Though tiki culture has gone in and out of fashion, the Tonga Hut has always been flying the flag in Los Angeles.

Most famous work of one of Frank Lloyd Wright's sons.

Giant Redwood-themed cafeteria operates under the golden rule, "Dine Free Unless Delighted."

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

A carousel trades in its classic horses and calliope for endangered species, native flora and fauna, and a modern soundtrack.

This opulent hotel has been visited by Spider-Man, Charlie's Angels, and the Ghostbusters.

Scores of vintage street lamps shine along L.A.’s Miracle Mile.

The final resting place of a space program monolith.

The programmatic glory of LA's giant whiskey barrel building has become an upscale reminder of the city's kitschy roadside past.

World-famous, Pink's still manages to keep its prized cult fetish status.

The private clubhouse for the members of the Academy of Magical Arts.

Resting place of Hollywood's immortals is also site of summer film screenings.

Oldest building in California still in use.