Ancient Political Philosophy

This link to the Stanford Encyclopedia of Philosophy discusses Ancient political philosophy, and includes a specific section on politics in Ancient Greece. It defines the Greek polis, and Greek ideas of justice. It also goes into greater detail about Ancient Greek politics.
One interesting quote from the page that displays the importance of justice to the Ancient Greeks: "So understood, justice defined the basis of equal citizenship and was said to be the requirement for human regimes to be acceptable to the gods."

You can scroll throughout the page to read more about Ancient Greek political philosophy:
Ancient Political Philosophy