North Brother Island, East River, New York City, United States

North Brother Island is a small island in the East River situated between the Bronx and Riker's Island, New York City. Once the site of a hospital, it is now uninhabited and designated as a bird sanctuary. It measures approximately 400 m by 250 m. Its smaller companion, South Brother Island, is a short distance away. Together, the two Brother Islands, North and South, have a land area of 20.12 acres (81,400 m2).
History
The island was uninhabited until 1885, when Riverside Hospital moved there from Blackwell's Island (now known as Roosevelt Island). Riverside Hospital was founded in the 1850s as the Smallpox Hospital to treat and isolate victims of that disease. Its mission eventually expanded to other quarantinable diseases.