Grand in scale and unique in design, Apartment 1-2Z is the only residence of its kind at 173-175 Riverside Drive, a distinguished J.E.R. Carpenter cooperative. With its private Riverside Drive entrance and two expansive floors totaling approximately 3,000 square feet, this grand four-bedroom apartment has the feel of a house and the advantages of full-service staffing. The formal entrance on Riverside opens to a gracious marble-floored foyer that evokes the entrance to a Gilded Age mansion. Finished in Venetian plaster and flanked by two large coat closets, the foyer opens to a sequence of oversized living spaces that comprise the home’s living and entertaining level. French doors open to the Riverside-facing living room, appointed with a decorative fireplace, ornate moldings, and built-in cabinetry with black granite surfaces. The adjacent formal dining room overlooks the landscaped courtyard and can host gatherings on a grand scale. A central gallery with a stained-glass ceiling and granite bar offers an additional entertaining space, complete with a walk-in closet and 146-bottle Sub-Zero wine refrigerator. This level also includes a quiet home office or fourth bedroom with additional refrigerated wine storage and a spacious eat-in kitchen, both facing the quiet planted courtyard. The Kitchen features granite counters, Sub-Zero refrigerator, a five-burner cooktop with double wall ovens, and two sinks. A black-granite staircase with an original wrought-iron railing leads upstairs to three remarkable bedrooms. The primary suite, nearly matching the scale of the living room, faces Riverside Park and features a decorative fireplace, picture-frame moldings, and three closets. Two additional king-sized bedrooms share a large full bath, and a full-size, vented laundry room is located on this level for convenience. Spanning the block between 89th and 90th Streets, 173-175 Riverside Drive is a full-service cooperative with 24-hour doorman, resident manager, and a dedicated staff of porters and maintenance personnel. Amenities include a fitness center, storage lockers, bicycle room, pet-washing station, playroom, and game room. Up to 50% financing is permitted; a 2% flip tax is paid by the buyer. Set across from Riverside Park and moments from the shops, dining, and services of the Upper West Side, this location offers both convenience and tranquility. A rare maisonette of this size, scale, and character—paired with the services of a premier cooperative—comes to market infrequently; viewings are available by appointment.