Answer:
The most powerful city-state in Italy was Rome. The city-state of Rome emerged as a dominant power in the Italian Peninsula around the 4th century BC, with a system of government headed by two consuls.
Rome became the most powerful state in the world by the first century BCE through a combination of military power, political flexibility, economic expansion, and more than a bit of good luck.
The Romans first conquered the neighboring city-states of Italy, such as the Etruscans, Samnites, and Greeks. Then, they began to expand their territory outside of Italy, conquering territories such as Spain, Greece, and parts of Africa and the Middle East.
The Romans also established colonies in newly conquered territories, which helped to spread Roman culture and influence. They also formed alliances with some conquered territories and incorporated them as Roman allies, which allowed them to expand their influence without direct military conquest.