Brookline is a town in Norfolk County, Massachusetts, United States, and part of the Boston metropolitan area. Brookline borders six of Boston's neighborhoods: Brighton, Allston, Fenway–Kenmore, Mission Hill, Jamaica Plain, and West Roxbury. The city of Newton lies to the west of Brookline. Brookline was first settled in 1638 as a hamlet in Boston, known as Muddy River; it was incorporated as a separate town in 1705.