Old Greenwich is a neighborhood/section and census-designated place in Greenwich in Fairfield County, Connecticut, United States. As of the 2010 census it had a population of 6,611. It was founded in 1641. Old Greenwich has become extremely popular for home buyers and ranks at 6th place in a March 22, 2017 Bloomberg report, "America's 100 Richest Places".The town of Greenwich is one political and taxing body, but consists of several distinct sections or neighborhoods, such as Banksville, Byram, Cos Cob, Glenville, Mianus, Old Greenwich, Riverside and Greenwich. Of these neighborhoods, three have separate postal names and ZIP codes.One of the founding settlers of Old Greenwich was Elizabeth Fones, niece and daughter-in-law of John Winthrop, founder and Governor of the Massachusetts Bay Colony.