The territory of Incorporated cities in Georgia is often circular, giving a stroking appearance on the map. They do not cover most of the urbanized territory. I would guess that half of Atlanta’s population of 5.9 million lives directly under one of the 20 county governments. There is a City of Atlanta, but it accounts for less than ten percent of the metropolitan population.
Atlanta is actually a suburb of Decatur, Georgia. When the railroad, around 1840, wanted to put a junction and yard in Decatur, the city fathers told the railroad to put this establishment at some distance. The settlement around the yards was called in rapid succession Terminus, then Marthasville, then Atlantica-Pacifica, then Atlanta.
Atlanta’s airport, Hartfield-Jackson, is by some standard the busiest in the country. But it is the only major airport I know where the arrivals and departures are still on the same level. The hub and spoke system was invented here by Delta Airlines in the early seventies or before, years before other carriers adopted it.