Situated on two flat acres of beautifully landscaped grounds along one of Old Westbury's most sought-after and prestigious streets, 9 Applegreen Drive is a striking contemporary estate offering exceptional privacy, scale, and luxury amenities. Surrounded by lush, mature plantings, the property provides a serene, park-like setting rarely found in such a prime location. A dramatic spiral staircase creates an unforgettable first impression upon entering the residence, setting the tone for the home's distinctive contemporary architectural character. Designed for both comfortable living and grand-scale entertaining, the home features 5 spacious bedrooms and 9 bathrooms (7 full and 2 half), with every bedroom enjoying its own private en-suite full bathroom. The luxurious primary suite serves as a private retreat, highlighted by a spa-inspired bathroom complete with an in-home sauna. A conveniently located first-floor laundry room enhances everyday functionality and ease of living. The chef's kitchen is equipped with premium Sub-Zero, Wolf, Bosch, and Miele appliances, along with a newly installed trash compactor, offering exceptional functionality and refined design. Complementing the main kitchen is a fully equipped butler's pantry functioning as a secondary kitchen, complete with its own refrigerator, stove, and microwave, ideal for entertaining, catering, and everyday convenience. The residence has been meticulously maintained and enhanced with numerous recent improvements, including new basement flooring, a new boiler, a new water heater, and updated deck, all installed within the past year. Outdoor living is equally impressive. A wraparound deck spans the rear of the home, providing the perfect setting for relaxing or entertaining while overlooking the expansive grounds. The estate also features a Har-Tru tennis court and a gunite swimming pool with newly installed pumps, creating a true resort-style experience. Adding tremendous versatility and value is the fully equipped pool house, thoughtfully designed for year-round enjoyment with its own dedicated heating and cooling systems. The pool house features a full kitchen complete with refrigerator, stove, and microwave, a comfortable living area, a full bathroom, dedicated washer and dryer, and charming herringbone brick flooring that creates a warm, rustic ambiance throughout the space. Whether used for entertaining, hosting guests, or relaxing poolside, the pool house offers a complete private retreat. Additional highlights include an attached two-car garage, a recently installed cesspool, freshly resealed driveway, brand-new sprinkler pump and heads, robust 400-amp electrical service, and an additional 150-amp service dedicated to the pool house and cabana amenities. Combining striking contemporary architecture, extensive capital improvements, resort-style amenities, and an exceptional location in the heart of Old Westbury, 9 Applegreen Drive presents a rare opportunity to own a meticulously maintained estate in one of Long Island's most coveted luxury enclaves.