This state-of-the-art retreat boasts impeccable design on a .6-acre parcel in the Upper Back Bay. Set behind private gates, this compound-like residence features more than 12, 300 sq. ft. of living space, 5 en-suite bedrooms, 10 baths, a soundproof home theater with memory foam carpet, game room, office, wine cellar, an attached guest house with private entry, two garages for 11 cars or a spacious home gym, Falsken water filtration system, and much more. No expense was spared in this refined custom estate with premium finishes throughout, including limestone flooring and baseboards, 12 ft. wood beam ceilings, and palatial corridors. The gourmet kitchen is fitted with state-of-the-art appliances, leathered granite kitchen counters, a butler's pantry, and two kitchen islands with scratch and stain-resistant kedra countertops. The resort-style backyard showcases a pool/spa, outdoor shower, and massive loggia replete with lounge areas, bar, and a 1, 500 sq. ft. covered outdoor kitchen featuring a built-in BBQ with a rotisserie grill, warming drawer, oversized glass refrigerator, nugget ice machine, and more. The 1, 000 sq. ft. principal suite occupies its own wing, with an office or nursery space, boutique-style walk-in closet, spa bathroom, and fireplace. Conveniently located on the upper level, is a full-sized laundry room with dual washer and dryer units and a dog washing station; a third laundry set is situated in the lower-level butler's pantry. The entire main house is wired to a generator in case of a power outage and is equipped with built-in audio, and extensive video surveillance and monitoring system.