Introducing 31 Chestnut Hill Drive, an extraordinary contemporary estate situated on five private acres at the end of a prestigious cul-de-sac in Upper Brookville. Originally designed by renowned architect Gary Gallagher and comprehensively reimagined from 2023 to 2026 by award-winning architect Stuart Narofsky, this exceptional residence seamlessly blends striking modern architecture with sophisticated design, cutting-edge technology, and resort-style amenities. Spanning over 10,000 square feet, the home features six bedrooms, six full and four half bathrooms, including a luxurious first-floor primary suite. Dramatic architectural details, including two custom floating staircases with glass railings, expansive walls of glass, porcelain flooring, and polished white oak floors, create a remarkable sense of openness and light. Thoughtfully designed living and entertaining spaces are complemented by a state-of-the-art chef's kitchen featuring custom cabinetry, integrated Thermador appliances, specialty quartz countertops, and an expansive center island. The home's extensive accommodations include multiple home offices, a library, and beautifully appointed guest suites. The fully finished lower level offers an exceptional collection of recreational and wellness amenities, including a Dolby Atmos home theater, custom wine room and tasting area, wet bar, fitness room, Finnish sauna, and dedicated yoga and massage space. Outdoors, the estate unfolds into a private resort-like setting, complete with a newly rebuilt heated saline pool and spa, expansive porcelain patios, and a fully renovated guest/pool house with its own kitchen. An outdoor kitchen and beautifully landscaped grounds provide an ideal setting for both intimate gatherings and large-scale entertaining. Additional highlights include a heated four-car garage, five-zone energy-efficient climate control, whole-house generator, and comprehensive smart-home technology managing lighting, security, motorized shades, and numerous additional systems. Offering exceptional privacy, architectural distinction, and an extraordinary level of modern luxury, 31 Chestnut Hill Drive represents a rare opportunity to experience contemporary estate living on Long Island's Gold Coast.