High Quality Content by WIKIPEDIA articles! Somerville is a city in Middlesex County, Massachusetts, United States, located just north of Boston. As of the 2000 census, the city had a total population of 77,478 and was the most densely populated municipality in New England. It is also the 17th most densely populated incorporated place in the country. It was established as a town in 1842, when it was separated from the urbanizing Charlestown. Somerville was a 2009 All-America City Award recipient.