The stately Prewar building at the corner of Fifth Avenue and 83rd Street is one of the city’s most prestigious and iconic. When the current owners of this distinctive 8,000-square-foot simplex—an esteemed architect and her husband—undertook its transformation, the intent was to create a stunning, spacious modern home while honoring the building’s history, style, and essence. The result is a residence that is both contemporary and timeless. Linked by a series of doors, the public spaces—a formal dining room, an expansive living room, and an inviting library—make a marvelous enfilade of sophisticated living and entertaining areas with an effortless flow and a magnificent view stretching down Fifth Avenue. In the autumn, the dining room looks out at the fountains and lights of the Met Plaza, and in summer, trees form a veritable green curtain of privacy from the street below. While ceiling heights have been maximized, in a nod to the building’s provenance, original details such as decorative moldings and window mullions were thoughtfully retained, re-created, or reincorporated. For floors in the living spaces, wood planks are arranged in a classic chevron pattern. Oak floors in the front of the home have a hand-wire-brushed finish that accentuates the natural wood graining and conjures an ageless Old World look. For flooring elsewhere, limestone was laid and ground in place for a sense of smooth seamlessness. Furniture-quality millwork in the bar, window surrounds, and transitional spaces was carefully hand-wire-brushed, resulting a unique texture and gloss quite deliberately recalling a Steinway. Custom-crafted by an artisan in Massachusetts, the unique library millwork is wire-brushed ebonized larch with a hand-applied matte Italian lacquer finish. The chef’s kitchen is steadfastly sleek, with a marble-wrapped island as well as streamlined cabinetry and stainless-steel appliances. Long-plank hardwood flooring adds a touch of organic softness and warmth. A butler’s pantry and a formal breakfast room adjoin. Private quarters enjoy a serene orientation, down a quiet hallway and overlooking 83rd Street. Each of the five guest bedrooms—one of which currently functions as a home gym—is accompanied by an en suite bath with a unique palette. A stylish oasis, the owners’ bedroom features hardwood floors in lengthy handsome planks, a lighted nook for the bed, and a warming fireplace. The suite also includes a remarkably chic, impeccably outfitted closet and dressing space. In the owners’ dual baths—linked by a striking shared glass-walled shower—a single slab of marble was templated and painstakingly placed for continuity of swirls and veining. Also along the hallway is a cheerful, casual den with a fireplace, eye-catching molding and millwork, and two wide, sunny windows. The busy professional will appreciate the bright, light-flooded office, which includes a wall of built-in shelving. The centrally located laundry area offers a generous collection of closets. Technological amenities abound. Extremely discreet air handlers in every room allow for limited ductwork and independent temperature control in each space. Walls are ideal for the display of art, for which humidifiers help maintain proper conditions. Audiovisual systems have been thoroughly updated and consolidated. Appliances are centrally monitored and appointed with leak detectors. A smart CoolMasterNet device allows for management of HVAC systems via phone or tablet. The home can be accessed by four elevators. Directly across the street from the Metropolitan Museum of Art and Central Park, the building is also steps from many of the city’s other museums—from the Guggenheim to the Neue Galerie—as well as other conveniences and attractions. Residents enjoy an array of amenities, including a 24-hour door attendant, a marble-clad lobby, a resident manager, a fitness center, and storage space.