The Town of Brookline, as it is officially called, separated from Boston, MA
on November 13, 1705. It is now a somewhat upscale town...still alongside Boston.
The State of Massachusetts tells us that the total area of Brookline is 6.82 sq. miles with a population of 54,718. It has several major streets including Beacon Street and Commonwealth Ave. One of its interesting "areas" is "Coolidge Corner", located at the corner of Harvard St. and Beacon St. In this area is an excellent theater, some great restaurants, and great shops (a Gap, Barnes & Noble, the Brookline Booksmith, etc.)
Although Brookline is historically known for 83 Beals Street, the birthplace of JFK, if you asked most thirtysomethings in Brookline what its most prominent feature is, you are just as likely to get an answer like "Parking is prohibited". Of course, this is an exaggeration, parking is allowed for two hours during the day and one hour at night. If you're a business, you can get an exemption.
As far a being a nice place to live, Brookline certainly qualifies. It has a very low crime rate, probably due to a massive police presence, town regulations prohibiting stores from being open beyond a certain hour (I'm not sure what hour that is, but let's just say that the "Store 24" is closed by 3am)