Marlborough is a town in Hartford County, Connecticut, United States. It contains the census-designated place (CDP) of Terramuggus. The population was 5,709 at the 2000 census. Marlborough is an upper class suburban and rural community. The local high school is RHAM High School. In 2012, Marlborough ranked #1 (of 24) in Connecticut Magazine's biannual ranking of Connecticut small towns, population 3,500 to 6,500.