Marlborough is a city in Middlesex County, Massachusetts, United States. The population was 36,255 at the 2000 census. It is home to Marlboro Airport. Spelling and pronunciation The name is sometimes spelled Marlboro, rather than Marlborough, which is the official spelling. The Boston accent tends to elide the first two syllables of 'Marlborough', producing the spoken name (by residents) 'MALL-bro', or 'MAh-bro'. 'MAR-Burrow' is the sort of compromise pronunciation by those relatively new to the area. It is usually pronounced 'Marl-burrow' by outsiders and people not familiar with the area.