New York City owns a creepy island that almost no one is allowed to visit - here's what it's like

Less than one mile from Manhattan - one of the priciest and most densely populated places in the world - exists a little-known island that people abandoned nearly 55 years ago.

"North Brother Island is among New York City's most extraordinary and least known heritage and natural places," wrote the authors of a recent study about the location by the University of Pennsylvania.

The city owns the 22-acre plot of land in the East River, which sits between the South Bronx's industrial coast and Riker's Island Correctional Center - New York City's most infamous prison.

Almost no one is permitted on North Brother Island and its smaller companion, South Brother Island, except for birds. But even they don't seem to want to live among its crumbling, abandoned structures (and contrary to Broad City's depiction of the island, there is no working package pick-up center).

However, Business Insider recently took a tour as part of a TV shoot, whose producers obtained permission from the city to go.

Here's what we saw and learned while romping around one of New York's spookiest and most forgotten places.