Over at The Kingston Lounge, Richard Nickel Jr. has posted some gorgeous photos of North Brother Island—including a brief history lesson and update on the current state of the place, which has been abandoned for 48 years. The island is in the Hell Gate section of the East River, and was once home to "a quarantine hospital that housed Typhoid Mary, was the final destination of the General Slocum during its tragic final voyage, and was the site of an experimental drug treatment program which failed due to corruption."
The hospital on the island was called Riverdale Hospital, and it treated smallpox, venereal diseases, heroin addiction, leprosy... you get the idea. Currently the island and its 12 remaining buildings (and tennis court!) are in a Grey Gardens-esque state, with most New Yorkers unaware that it even exists. Now under the jurisdiction of the Parks Department, it will remain a protected nesting area, off-limits to the general public, and the city currently has no plans to rehabilitate the buildings.
There is also a South Brother Island—purchased by the city in 2007—right next door; together they contain 20.12 acres of land (here's an aerial view). While they're considered a part of the Bronx now, up until the late 1960s they were considered to be a part of Queens County.