Exceptional owner-occupied and investment opportunity in Portsmouth's coveted South End. This beautifully updated legal two-unit property combines the charm of a historic home while offering the ideal blend of lifestyle and cash flow. You'll love the flexibility of the layout as well which can be configured as a single family home, or side-by-side duplex, or it's current layout as a home with a 2-room studio apartment. The owner's residence is filled with timeless New England character while offering thoughtful modern updates throughout. The attached studio features its own private entrance, efficient layout, and a spa-inspired bathroom complete with a private sauna, creating a memorable guest or tenant experience. Outside you'll enjoy morning coffee or evening cocktails on your spacious, private back patio - and a private patio for the apartment as well! The oversized shed offers fantastic storage, a work shop, or garage potential. Originally built circa 1750, the property underwent extensive exterior renovations in 2025, including a new roof, four skylights, new windows, cedar siding on the front façade, Hardie® cement board siding on the sides and rear, and blown-in insulation. Additional features include natural gas heat (new furnace being installed prior to closing), public water and sewer, two 100-amp panels, a detached storage shed, and 1 off-street parking spot. Located just steps from Prescott Park, Strawbery Banke, the Piscataqua River waterfront, and Portsmouth's renowned restaurants, boutiques, and entertainment, this is a rare opportunity to own an income-producing property in one of New England's most desirable coastal communities. Whether you're looking to offset your mortgage with rental income, expand your investment portfolio, or enjoy the flexibility of a legal two-unit property in an unbeatable location, 491 Marcy Street offers exceptional value and endless possibilities. Showings start at open house, Saturday July 25th, 12 to 2pm.