Rare opportunity to own this Gold Coast penthouse sitting atop a uniquely constructed James Lowenberg building. Designed by the late Marvin Herman of Marvin Herman Architects & Interiors - esteemed for bespoke craftsmanship, fine millwork, and classical proportions thoughtfully adapted for elevated urban living throughout Chicago's Gold Coast and Magnificent Mile - this 2,500 sq. ft. luxury home, affectionately known as "Joyau du Ciel" (Jewel of the Sky), reflects an exceptional use of space and grand-scale finishes. Impeccably maintained, the residence seamlessly combines sophisticated design, timeless architectural detail, and refined comfort. The home features floor-to-ceiling windows throughout, as well as two balconies with east- and south-facing views, offering breathtaking, unobstructed vistas of Lake Michigan and the iconic Chicago skyline. The open-concept living and dining areas flow seamlessly into a chef's kitchen featuring ample granite counter space and a full wraparound bar with seating for six or more. Ageless Crema Marfil marble flooring in a warm, subtle hue and premium custom Anigre cabinetry are the crowning touches to this elegant space. The thoughtfully designed primary suite offers a large mirrored wardrobe and luxurious individual his and hers bathrooms featuring an oversized Jacuzzi tub, a rain shower, and a separate water closet. An adjacent den with full-size washer/dryer, currently used as a home office, completes this private retreat. Additional highlights include expansive attic storage space; noise-cancelling insulation behind 3/4" drywall in all exterior and interior walls; solid wood doors & trim throughout; copper risers ground-to-faucet; surround sound system and black-out drapes; two parking spaces conveniently located directly across from one another; visitor parking on a separate garage level; and access to exceptional building amenities, including a sundeck, health deck, and discounted membership opportunities with FFC Fitness. All custom furniture negotiable, including a dining table with seating for 14; an Estonia grand piano; a Herman Miller grandfather clock. Located in the heart of Chicago's prestigious Gold Coast neighborhood, this residence offers unparalleled access to some of the city's finest dining, shopping, nightlife, and lakefront attractions. Just moments from the Restaurant Triangle/Mariano Plaza, Washington Square Park, Magnificent Mile, Oak Street Beach, Lakefront Trail and CTA Red Line, residents enjoy the perfect blend of vibrant urban energy and refined residential charm. DETAILED VIRTUAL TOUR AVAILABLE UPON REQUEST.