a town of North America, state of Massachusetts, and county of Middlesex; situated on a peninsula formed by the Charles and Mystic rivers, one mile N. of Boston, with which, as also with Chelsea, Malden, &c., it is connected by bridges. It contains the Massachusetts state prison, lunatic asylum, town-hall, and United States navy-yard covering 60 acres of land, and which has a marine hospital, extensive warehouse, arsenal, and powder magazine. Breed's or Bunker's Hill stands close to the town, and has a granite obelisk commemorating the battle fought there June 17, 1775. Charlestown may be considered as a suburb of Boston. It is a place of considerable trade, and had in 1850 17,216 inhabitants.