segment of the Appalachian Mountains, U.S., mainly in Berkshire county, western Massachusetts. Many summits rise to more than 2,000 feet (600 metres), including Mount Greylock (Greylock, Mount) (3,491 feet 【1,064 metres】), the highest point in Massachusetts. The scenic wooded hills are a continuation of the Green Mountains of Vermont; they include the Hoosac Range and Taconic Range (Massachusetts and New York) and the Litchfield Hills (Connecticut). The chief streams are the Deerfield and Westfield (east) and the Hoosic and Housatonic (Housatonic River) (west).

Crossed by the Appalachian National Scenic Trail (for hikers) and the Mohawk Trail scenic highway, the Berkshires have long been a favourite year-round vacation spot. Among the wilderness and recreation areas in the hills are Beartown State Forest, Mount Greylock State Reservation, and October Mountain State Forest. The Tanglewood Music Festival, in Lenox, is a major summertime attraction, and there are seasonal theatre and dance festivals in other towns.