By Mary Marsh
Turn down the 600 block of West 136th Street, and the traffic quiets. The buildings on this block are stately—columns at the entrance, elaborate floral pediments over the windows, swirling iron fencing on the fire escapes. Building 601 stands out from the rest because of the ornate cast-iron gate over its front doors. A detail like this seems like it might belong to a co-op on Park Avenue with a doorman and a valet. But this building is a co-op of a different kind—a Housing Development Fund Corporation, sold by the city directly to tenants in order to provide an opportunity for homeownership to low-income New Yorkers. Walk farther down the street, and you’ll encounter another, at 607, and then another, at 611. All told, this block houses six HDFCs, a total of 141 units of affordable housing. It isn’t just this block, though. Our own Community District 9, made up of Hamilton Heights, Manhattanville, and Morningside Heights, is a hotspot for these buildings, home to about 150 buildings of some of the most affordable housing in New York City....