City-State, self-governing, self-contained urban center, usually surrounded by a small dependent rural area. The typical city-state of antiquity was the Greek city, such as Athens, which had complete political independence. Rome in its early days was a city-state. During the period from the fall of the Roman Empire to the 19th century, many cities of northern Italy, such as Florence and Genoa, were city-states. Several north German cities also functioned as city-states, of which Bremen and Hamburg retained some independence well into the 19th century. As a separate and autonomous political unit, the city-state cannot exist within an empire or a modern national state.