Rare opportunity in Cowell Terrace featuring one of the largest, flattest, and most usable lots you'll find, just 2 miles from the Walnut Creek border! Situated on a massive, pancake-flat parcel spanning over half an acre that is tucked away at the end of a quiet street with no through traffic, 4130 Beryl Dr offers privacy, scale, and major potential that is increasingly hard to find. This single story 3 bedroom, 2 bath, approximately 2,220 sqft mid-century modern home features open beam ceilings throughout and a layout centered around natural light and indoor/outdoor living. The main living room includes a brick wood-burning fireplace and direct backyard access. A separate family room offers a second fireplace, vaulted ceilings, updated vinyl plank flooring, and near floor-to-ceiling windows that bring in abundant natural light. The kitchen captures Northeast-facing light and includes an island with cooktop and overhead hood, pass-through window to the living area, double oven, dishwasher, refrigerator, and tile counters. The spacious primary suite features open beam ceilings, yard views, and a dual sink vanity with shower. Secondary bedrooms are generously sized with consistent architectural character. Guest bathroom includes a full shower and is conveniently located off the main living space. Indoor laundry area includes 220V and gas hookups, utility sink, and houses HVAC and water heater. Newer AC unit installed in 2019. The lot is the true standout. Fully usable, flat, and expansive, this is the kind of property buyers wait years for. Whether you're envisioning a custom remodel, adding square footage, building an ADU, creating a resort-style backyard w/ pool, or exploring possible SB9 potential (lot split opportunity), the space is here to make it happen! Property offers a great opportunity for customization and updating to bring your vision to life. Fenced yard includes a large side yard, well-maintained lawn area, and a shed. Detached two-car garage with an attached shop offers flexibility for storage, workspace, or potential future use. Located near the end of a quiet, court-like street with no through traffic, just a short walk to Lime Ridge Open Space trailheads and Markham Nature Area, and minutes to Walnut Creek's dining, shopping, and nightlife. Properties with this combination of lot size, usability, location, and potential rarely come to market.