A four-bedroom, four-and-a-half-bath townhome that lives like a single-family. Your own front door off a covered porch. A private lawn. Deeded parking. And a roof deck off the primary suite unlike anything else in this part of Cambridge.The setting is Baldwin, the quiet, tree-lined pocket between Harvard and Porter Squares. Harvard Square, the Red Line, the Porter commuter rail, Harvard Law School and the city’s best restaurants and coffee are all a short walk.The main level has 9'4" ceilings and runs more than 33 feet end to end in one open space. The kitchen is 23 feet wide, with a bay window, a long center island and a full Thermador package. The 22-foot living and dining room gathers around a gas fireplace. A powder room and coat closet round out the first floor.On the second floor, two bedrooms each have a walk-in closet and two full baths plus side-by-side laundry machines complete the floor.The third floor is what sets this home apart. The whole level belongs to the primary suite: an 18-by-16-foot bedroom under soaring 11'2" ceilings, a walk-in closet and a full bath with walk-in shower. Step out and you’re on a private roof deck of roughly 22 by 21 feet, with room for a dining table and a lounge area both. A primary bedroom that opens straight onto open sky, at this size, is close to unheard of in this part of Cambridge.The lower level, with 8'4" ceilings, adds a 19-foot family room, a fourth bedroom and another full bath. Great for guests, a live-in nanny or a home office.Note: photos are of the adjacent mirror-image unit; finishes and layout are the same, reversed.