Set on a quiet hillside court in a well-established neighborhood, 1509 Lassen Court offers a wonderful blend of privacy, space, and versatility. This spacious five-bedroom home is ideal for comfortable everyday living, remote work, or multi-generational needs. Recent improvements include a new roof and gutter system, newly paved driveway, refreshed landscaping, brand-new range, ample kitchen cabinetry, fireplace, and beautiful hardwood flooring throughout. A truly unique feature of the home is the hidden lower-level flex space beneath the house, constructed entirely of solid concrete and accessed by an interior stairway. Measuring approximately 10′ x 20′ with roughly 7.5-foot ceilings and ventilation, this rare bonus area offers endless possibilities including a wine cellar, media room, hobby or art studio, fitness area, safe room, workshop, or additional storage. Enjoy partial city views and a covered backyard patio perfect for relaxing or entertaining. Conveniently located near schools, shopping, dining, Mare Island, and easy freeway access. (Some photos have been virtually staged.)