Old Greenwich, Connecticut 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 populace of 6,611. It was established in 1641.

The town of Greenwich is one political and taxing body, but consists of a several distinct sections or neighborhoods, such as Banksville, Byram, Cos Cob, Glenville, Mianus, Old Greenwich, Riverside and Greenwich (sometimes referred to as central, or downtown, Greenwich).

Of these neighborhoods, three (Cos Cob, Old Greenwich, and Riverside) have separate postal names and ZIP codes.

What is now called Greenwich Point was known for much of its early history as "Elizabeth Neck" in recognition of Elizabeth (Fones) Feake Hallet and their 1640 purchase of the Point and much of the region now known as Old Greenwich. The Old Greenwich Railroad Station, originally called the "Sound Beach Railroad Station", assembled in 1894 and added to the National Register of Historic Places in 1989, serves commuters in the neighborhood.

Old Greenwich was known as "Sound Beach" in the 19th century, and the chief road through the small downtown company section is Sound Beach Avenue.

Old Greenwich had an industrialized existence back in the 1950s/60s when Electrolux had a vacuum manufacturing facility on Forest Avenue, opposite "ECCman Center" (now Greenwich Civic Center).

It has a several distinct sections each with its own mailing address and ZIP code, such as Byram, Cos Cob, Glenville, Mianus, and Riverside and Greenwich proper (downtown Greenwich).

Old Greenwich has turn into extremely prominent for home buyers and now rates 69th by the Forbes 2015 most expensive zip codes in the country.

Geological Survey Geographic Names Information System: Old Greenwich, Connecticut