a post-town in Middlesex county, Massachusetts, one mile north of the centre of Boston. The principal part of the town is finely situated on a peninsula formed by Charles and Mystic rivers, which here flow into the harbour of Boston. Charlestown is connected with Boston by two bridges across Charles river, with Chelsea and Malden by two others across Mystic river, and with Cambridge by a bridge across a bay of Charles river. The town is pleasant and flourishing, and advantageously situated for trade and manufactures. One of the principal navy-yards in the United States occupies about sixty acres of land in the south-east part of Charlestown. Bunker's Hill, on which a general battle was fought during the American revolution, stands close to this town. The population in 1820 was 6591.