It started with the marble. Before any walls came down or paint swatches were selected, Andrea Fisk and Jess Thomas Hinshaw of Shapeless Studio took their clients—a young New York City couple who had recently made the move uptown to Harlem—to their first stone yard. “We probably looked at like, I don’t know, 100 different kinds of stone with them. But when they came to this one, their faces completely lit up,” recalls Fisk of the swirly, veined turquoise Calacatta. “Honestly it was like watching someone fall in love at first sight.”

“Before the renovation, the space was pretty unexciting,” reports Andrea Fisk of Shapeless Studio. “There were some exposed brick walls, small rental-quality kitchens that seemed at least 20 years old (one in each apartment), and standard 2 1/4-inch oak flooring.” To start, she and co-principal Jess Thomas Hinshaw—with structural engineer Tom Gasbarro, ABS Engineering, and Sunshine Renovations Management—started by stitching together the two units at the seams. Instead of thread, though, the two spaces are joined with steel and glass doors, a nod to the building’s industrial bones.