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 (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.
The original settlement of Glenville, which was formerly known as "Sherwood's Bridge", was listed on the National Register of Historic Places in 2007 as the Glenville Historic District. The district covers 33.9 acres (13.7 ha) and is the "most comprehensive example of a New England mill village within the Town of Greenwich". It "is also historically significant as one of the town's major staging areas of immigrants, predominantly Irish in the 19th century and Polish in the 20th century" and remains "the primary settlement of Poles in the town". Further, "[t]he district is architecturally significant because it contains two elaborate examples of mill construction, designed in the Romanesque Revival and a transitional Stick-style/Queen Anne; an excellent example of a Georgian Revival school; and notable examples of domestic and commercial architecture, including a Queen Anne mansion and an Italianate store building."