According to the United States Census Bureau, Brookline has a total area of 6.8 sq mi (17.7 km2), all but 0.039 sq mi (0.1 km2) (0.44%) of which is land.
The northern part of Brookline, roughly north of the D-line tracks, is urban in character, as highly walkable and transit rich. The population density of this part of town is nearly 20,000 inhabitants per square mile (8,000/km2), on a par with the densest neighborhoods in nearby Cambridge, Somerville and Chelsea, Massachusetts (the densest cities in New England), and just below that of central Boston's residential districts (Back Bay, South E...
Source: Wikipedia (as of 04/11/2019). Read more from Wikipedia