A hidden path at the National Theatre lets you look behind the scenes of the latest productions.

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

This overlooked street light once served as a KGB dead letter box.

At almost 1,000 years old, this is the oldest known door in all of Britain.

Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

Rat sculptures try to infiltrate the Graybar Building in an architectural tribute to New York City's nautical history.

A memorial to the first person killed by a motor vehicle in the Western Hemisphere.

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

More than 300,000 historical artifacts from the famous music venue, from Duke Ellington's handwritten score to The Beatles' booking slip.

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

An annual extravaganza of Broadway theater memorabilia.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

A bit of retro transportation flair preserved in the world's largest department store.

Nikola Tesla's former home contains an homage hidden from plain sight.

Test your business savvy and play the market for cocktails at this stock exchange-inspired watering hole.

Elevated freight railway turned wildly successful urban park.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

The best way to get a sneak peek at the movies.