In design circles in the 1970s, this midtown house was considered a momentous piece—the first notable reno by modernist architect Peter Hamilton. The house’s new owners, a doctor and an investment exec, loved the property’s multi-level concept but not its exposed heating ducts and glass blocks. They hired architect Ian MacDonald, who added soaring windows, removed walls, installed warm Brazilian cherry floors and relocated the living room and master bedroom to the back of the house for a view of the yard. Outdoors, there’s a new swimming pool, deck and fireplace. The four stainless steel chimneys that run the height of the home are MacDonald’s homage to Hamilton’s erstwhile ducts.