Roman Republic
Roman government was headed by two consuls, elected annually by the citizens and advised by a senate composed of appointed magistrates. As Roman society was very hierarchical by modern standards, the evolution of the Roman government was heavily influenced by the struggle between the patricians, Rome's land-holding aristocracy, who traced their ancestry to the founding of Rome, and the plebeians, the far more numerous citizen-commoners. Over time, the laws that gave patricians exclusive rights to Rome's highest offices were repealed or weakened, and leading plebeian families became full members of the aristocracy. The leaders of the Republic developed a strong tradition and morality requiring public service and patronage in peace and war, making military and political success inextricably linked. Many of Rome's legal and legislative structures (later codified into the Justinian Code, and again into the Napoleonic Code) can still be observed throughout Europe and much of the world in modern nation states and international organizations.

Q: What were Rome's legislative structures eventually turned into?
the Justinian Code