912 square feet:
The architect of this Upper West Side apartment extended the petite living space by installing an 8-by-15-foot sliding glass door, which leads to an outdoor dining area built six feet above the alley. To make the outdoors feel like it's part of the living room, and not a separate patio, they ran the same horizontal pattern of ipe wood slats from the indoors out.
Photo by Roland Bello. View Slideshow