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

A semi-scholarly approach to sex.

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

This semi-hidden Manhattan restaurant is based out of a loading dock.

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

A miniature rainforest is growing inside of a Midtown Manhattan office building.

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

A very classy 1920s-era bar right in Grand Central Station.

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

Read a book next to a Midtown waterfall.

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

Tucked away amidst some of the most famous addresses in the world is New York's only fraction of a street.

Slyly buy a shake in the Parker Meridien lobby.

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

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

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

The "Seinfeld" diner.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

The oldest house in Manhattan is now a museum that remembers the home's sordid history of scandals, vice-presidents, and ghosts.

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

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

A crumbling hospital from the 1850s on Roosevelt Island.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.