Chestnut Hill is an affluent New England village located six miles (10 km) west of downtown Boston, Massachusetts, United States. Like all Massachusetts villages, Chestnut Hill is not an incorporated municipal entity. Unlike most Massachusetts villages, it encompasses parts of three separate municipalities, each located in a different county: the town of Brookline in Norfolk County; the city of Boston in Suffolk County (parts of its neighborhoods of Brighton and West Roxbury), and the city of Newton in Middlesex County. Chestnut Hill's borders are roughly defined by the 02467 ZIP Code. Chestnut Hill is not a topographical designation; the name refers to several small hills that overlook the 135-acre (546,000 m²) Chestnut Hill Reservoir rather than one particular hill.