The real "key" to this East Glencoe stunner is its rare balance of fine architectural detail, luxurious lifestyle living, and unbeatable location where every day feels like a getaway with access to your own private association beach just down the block. Set high at the end of a coveted cul-de-sac with lake breezes, this stately white stucco Mediterranean home makes an unforgettable first impression. Crisp, clean lines, oversized black-inlay custom windows, and manicured landscaping hint at the curated sophistication inside. Step through grand glass doors into a dramatic two-story foyer, where 13.5-foot ceilings and walls of windows flood the home with natural light, creating an immediate sense of volume and calm sophistication. A Spanish pied-a-terre vibe flows throughout layered with character and craftsmanship: artisanal plaster trim, reclaimed wide-plank hardwood floors & full-height sliders that dissolve the boundary between indoors and out. Off the foyer, the formal living room offers the perfect spot for intimate fireside evenings, while the paneled office-wrapped in Farrow & Ball Hague Blue with bespoke built-ins-can easily flex into a first-floor bedroom thanks to an adjacent quartz-clad full bath. At the heart of the home a massive dining room bridges casual and formal living framed by arched millwork openings and oversized windows. Family room custom painted in serene monochromatic tones with Restoration Hardware style is anchored by a wall of French doors that open seamlessly to the newly designed backyard oasis-making indoor-outdoor entertaining effortless. The Chef's kitchen pairs beauty and function: dark grey custom cabinetry with Newport Brass hardware, a sculptural oversized range hood, high-end stainless appliances, and a large island with seating. Adjacent, the sunny breakfast room opens through a retractable Nano glass wall to a resort-level backyard featuring a built-in outdoor kitchen, dining pergola, cozy fire-pit lounge, and lush landscaping designed for year-round enjoyment. Practical luxury continues with a fully equipped mudroom featuring custom lockers, secondary laundry, a large walk-in pantry, powder room, and direct access to the attached three-car garage. Upstairs volume and light continue along the extra-wide hallway leading to four spacious bedrooms. The primary suite is a sanctuary with dual walk-in closets and a Four Seasons-level marble bath wrapped in Calcutta Gold-complete with double vanity, soaking tub, steam shower, heated floors, and fixtures by Waterworks and Phylrich. A guest suite with private marble bath and walk-in closet sits nearby, while two additional bedrooms share a sophisticated Jack-and-Jill bath. A second laundry room adds daily convenience. The fully finished lower level offers endless recreation and entertainment with a full theater area, playroom, custom bar, and temperature-controlled wine cellar-plus a 5th bedroom with full bath for guests or live-in arrangements. Set on a half-acre of beautifully landscaped grounds, just one block from Harbor Street's keyed gate to your private beach, this residence captures the very best of North Shore living-award-winning New Trier schools, charming downtown nearby, and a 25-minute train ride to the city. Full of character yet aligned with every modern must-have, 320 Keystone stands apart for buyers who crave refined design, authenticity, and a touch of everyday magic-not another cookie-cutter new construction home.