Discover the perfect blend of luxury, privacy, and nature in this exquisite 4-bedroom, 2.5-bath home, nestled at the top in Alta Loma’s foothills of Rancho Cucamonga. Spanning 2,800+ sq. ft. of living space on a half-acre horse property parcel (20,900 sq. ft.), this residence offers an unparalleled living experience with breathtaking views. As you arrive, you’ll be greeted by lush landscaping, mature trees providing shade from the summer sun, and perhaps even a visit from the local deer family. Step through the double-door entry into a bright and airy living room with soaring vaulted ceilings and expansive windows framing stunning mountain views. Designed for Comfort & Entertaining is the living and formal dining area – The perfect setting for intimate dinners or festive gatherings. The updated Open-Concept Kitchen features a breakfast bar for casual seating and a seamless flow into the family room, ideal for everyday living or entertaining close to the fireplace on those cool winter nights or a warm ambiance. The 570+ sq. ft. bonus room (permitted) addition with French Doors can easily transform into a downstairs master suite, game room, or recreation space with direct backyard access that opens to a fully shaded, private oasis with a stand-alone covered gazebo, perfect for unwinding in nature's beauty. From there, you can stroll towards your very own tree-shaded retreat, a custom-built 10x12 cottage—perfect for a home office, creative studio, or peaceful escape. Direct access to the 20-foot-wide city-maintained community horse and recreational trail, perfect for riding, hiking, or mountain biking. Backing up to miles of scenic trails provides endless opportunities for outdoor adventures. Top-rated award-winning Alta Loma School District (ALSD’s) Hermosa Elementary, Vineyard Jr High, and the Los Osos High School are nearby. This is more than just a house—it’s an investment in a lifestyle of tranquility, elegance, and natural beauty. Don't miss your chance to make 10139 Sun Valley Dr your personal retreat in one of Rancho Cucamonga’s most sought-after neighborhoods, “The Woods”. Note: Buyer and Buyer’s Agent are advised to conduct any and all inspections and to independently verify the accuracy of information found in the MLS, such as square footage, lot size, zoning, permits, and other details.