A dark, dank room in subterranean Manhattan was the site of a ghastly murder.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.

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

An unassuming secret door once led to a legendary watering hole.

Unique antiquarian shop specializing in globes, maps, and prints.

The oldest surviving synagogue in New York City is now a soaring art space.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

A celebration of capitalism in Midtown.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

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

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

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

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

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

New York City's smallest piece of private property.

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

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

One of only two commuter aerial tramways in the United States.

Read a book next to a Midtown waterfall.

A dilapidated dock tells the story of Titanic's missed arrival.

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

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

A hands-on traveling collection of the innovative devices of yesteryear.