The Octagon Roosevelt Island is one of New York City’s quirkiest areas, a little dollop of land halfway between Manhattan and Queens that used to house a notorious mental hospital. It’s since been torn down and rebuilt as a luxury apartment building called the Octagon. If there’s one thing we’ve learned from horror movies, it’s that tearing down a building doesn’t get rid of ghosts, and residents have reported all kinds of extranormal shenanigans,.