Acharnes is a suburb and a municipality in Attica, Greece, in the East Attica regional unit. With 108,169 inhabitants, it is the ninth most populous municipality in Greece. It is part of the Athens urban area.

Attica, or the Attic Peninsula, is a historical region that encompasses the entire Athens metropolitan area, which consists of the city of Athens, the capital of Greece and the core city of the metropolitan area, as well as its surrounding suburban cities and towns. It is a peninsula projecting into the Aegean Sea, bordering on Boeotia to the north and Megaris to the west. The southern tip of the peninsula, known as Laurion, was an important mining region.