Red frames showcase remnants of one of New York's original subway stations.

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

The first piece of public art dedicated to LGBT rights.

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

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

An artist's cute bronze subway sculptures belie his violent artistic past.

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

A small part of lower Manhattan is actually made from a bit of England.

A whimsical, but often overlooked clock in Park Avenue.

NYC's legendary underground network for bovine transportation.

Join in a Seance at the Swedenborgian Church.

There must be a pun in this haystack somewhere...

A replica of a 7th-century church hides in plain sight in the middle of the concrete jungle.

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

A small peaceful park and waterfall tucked amid the urban grind of Midtown Manhattan.

This Upper East Side apartment co-op was designed as a tuberculosis sanitarium.

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

The front yard of an Upper East Side town house hides the last fragment of one of New York's most famous theatres.

A basement pool hall is the front for some of the best Dominican food in New York City.

Beautiful mosaics cover the first stations opened on New York City's newest subway line.

This hidden library of physiological ephemera contains centuries worth of knowledge on the vim and viscera of the human body.

For over 30 years the walls of this Harlem schoolyard have been a gallery of street art by "Kings and better."

Hiroshima survivor on Riverside Drive.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.