Greek city-states were known as a polis. The acropolis was the main gathering place. The acropolis also served as a religious center where temples and alters were built to honor their many gods and goddesses. The agora served as a market place and a meeting place. Most city-states were small, but Athens had as many as 300,000 people.
The polis was run by its citizens. Citizenship meant:
you were a member of a political community you were a native born man you owned land