The first green space constructed on an elevated viaduct.

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

This secluded walkway overlooks a magnificently wild London green space.

The Columbia Road Flower Market is now open every Sunday, rain or shine.

This hidden green space is the city's second largest conservatory.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

This Parisian café sticks almost exclusively to an ethos of reuse.

Some locals believe the fabled lost gold of General Yamashida is hiding somewhere beneath the city.

Five miles of underground river link lake to ocean.

Dozens of lights dangle from the branches of what may be the brightest tree in Los Angeles.

The house where Good Will Hunting was written is a surreal fairytale abode.

Two men, two visionaries of Venice Beach, one little hotel that smells like cookies.

The neighborhood shop is a sort of tiny cactus museum full of exotic specimens you can take home.

Mysterious glowing orbs float through the desert night.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

Thanks to a quirk of elevation this gift shop produces magic doughnuts that are found nowhere else on Earth.

Neon signs that grace the windows of Bergdorf Goodman's and Tiffany & Co. come from this studio in Brooklyn.

A hidden subterranean installation offers a view of the sky.

An Escher-inspired library dedicated to the wonders of the human mind, yet closed to the public.

The abandoned personal amusement park of the King of Pop.

This rare example of a "tidefall" is a spectacular drop from the cliffs down onto the beach.

A 90-year-old underground water reservoir offers a more industrial kind of tranquility.