Rare opportunity in Duarte! For the first time in decades, 1900 S. Mountain Avenue is available. This property offers endless potential on one of the largest lots in the neighborhood. The main residence features 3 bedrooms, 2 bathrooms, and 1,660 sq. ft. with a spacious floor plan that includes an indoor laundry room. Set on a massive 27,400+ sq. ft. lot (0.63 acres), the grounds are fully fenced with an automatic entry gate and boast mature landscaping, including fruit-producing lemon and orange trees. A detached bonus studio with full bath and kitchen setup provides flexible options for guests, extended family, office, or rental potential (not included in recorded square footage). Oversized parcels of this scale are rarely available, making this an ideal opportunity for investors, developers, or visionaries seeking expansion, multiple units, or the chance to create a one-of-a-kind retreat. Conveniently located near schools, shopping, freeways, and the foothills of the San Gabriel Mountains, this property offers both immediate livability and long-term upside.