Watertown is a town in Middlesex County, Massachusetts, USA. Watertown was settled in 1630 by Colonists under Sir Richard Saltonstall. In 1631 the townspeople declined to pay a tax of 60 pounds levied by the 'assistants', thus protesting against their autocratic rule, which bore fruit in the establishment of a more popular governmental plan in 1632. In 1775 the Provincial Congress met at Watertown.