Atlanta is about 3.7 times smaller than Rome.

Rome is approximately 1,287 sq km, while Atlanta (map shows its 114 named neighbourhoods; the area covers the whole city) is approximately 350 sq km, making Atlanta 27.22% the size of Rome.
Tip: This to-scale comparison of Rome vs. Atlanta uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.