Crowning one of Back Bay's most coveted addresses, this one-of-a-kind 6,000 SF penthouse duplex offers a rare combination of grand entertaining spaces and comfortable family living. From its dramatic floor-to-ceiling windows, the residence showcases sweeping, front-row views of the Charles River, Cambridge skyline and City beyond. The elevator opens directly into a gracious foyer, introducing an impressive living room with soaring ceilings and refined moldings, all oriented to capture the River and skyline views. Adjacent, a richly paneled study with fireplace and wet bar creates a warm retreat for work or relaxation. The formal dining room flows seamlessly into a spacious eat-in kitchen, ideal for both casual meals and large-scale entertaining. The upper-level features 6+ generously sized beds and 6 full baths, including a tranquil primary suite. Separate 1 bed/1 bath condo at 270 Beacon Street included. Co-op fee includes real estate taxes and management fee.1 garage & 2 outdoor spot