Set along one of Washington's most iconic avenues in the heart of sought-after Cleveland Park, 3721 Massachusetts Avenue NW presents a rare opportunity to own a classic residence rich with original character and timeless architectural details. This distinguished three-story home offers exceptional scale, solid construction, and meaningful recent improvements throughout. A stone entry introduces warm and inviting interiors featuring hardwood floors, graceful archways, crown molding, and abundant natural light throughout. The main level includes a welcoming foyer with powder room, an elegant living room anchored by a fireplace and bay window, a formal dining room ideal for entertaining, and an updated kitchen featuring a commercial range and direct access to the rear patio and garden. The upper level features a spacious primary suite with en-suite bath, along with two additional bedrooms and a hall bathroom. The lower level provides flexible additional living space with a half bath and utility area, offering endless possibilities for a recreation room, guest suite, home office, gym, or future customization. Significant seller improvements include the installation of a high-efficiency mini-split system, updates and repairs to the slate roof, refinished hardwood floors throughout, the addition of a commercial range and new refrigerator in the kitchen, new custom blackout drapes, and extensive fencing and gate improvements. These thoughtful updates enhance both the comfort and functionality of the home while preserving its enduring architectural character. Outside, the private rear garden is framed by mature plantings and features a patio ideal for outdoor dining and entertaining, while a detached garage with alley access adds convenience and functionality. Ideally located near neighborhood parks, acclaimed schools, and the shops and restaurants of Cleveland Park, Cathedral Commons, and upper Wisconsin Avenue, this special offering combines timeless charm, important recent upgrades, and exceptional long-term potential in one of Washington's most established neighborhoods.