A city-state is an independent or autonomous entity whose territory consists of a city which is not administered as a part of another local government. A city-state can also be defined as a central city and its surrounding villages, which together follow the same law, have one form of government, and share languages, religious beliefs, and ways of life. Today, only five independent, sovereign city-states exist: Monaco, Singapore, Vatican City, San Marino and Malta.
Historical examples include the oldest known Sumerian cities of Uruk and Ur, the Phoenician cities (such as Tyre and Sidon), the Berber city-states of the Garamantes, the city-states of ancient Greece (the poleis such as Athens, Sparta, Thebes, and Corinth), the Roman Republic which grew from a city-state into a great power, the Maya, Aztecs, and other cultures of pre-Columbian Mesoamerica (including cities such as Chichen Itza, Tikal, Monte Albán and Tenochtitlan), the central Asian cities along the Silk Road, Venice, Croatian city-state of Ragusa (Dubrovnik) and many others. The Viking colonial cities in medieval Ireland, most importantly Dublin, have recently been classed as genuine city-states.
Within the transalpine part of the Holy Roman Empire the Free Imperial Cities enjoyed a considerable autonomy, buttressed legally by the Lübeck law which was emulated by many other cities. Some cities – though also members of different confederacies at that time – officially became sovereign city-states in the 19th century – such as the Canton of Basel City (1833–48), the Free Hanseatic City of Bremen (1806–11 and again 1813–71), the Free City of Frankfurt upon Main (1815–66), the Canton of Geneva (1813–48), the Free and Hanseatic City of Hamburg (1806–11 and again 1814–71) and the Free and Hanseatic City of Lübeck (1806–11 and again 1813–71). Another city-state, though lacking sovereignty, was West Berlin (1948–90), being a state legally not belonging to any other state, but ruled by the Western Allies. They allowed – notwithstanding their overlordship as occupant powers – its internal organisation as one state simultaneously being a city, officially called Berlin (West). Though West Berlin held close ties to the West German Federal Republic of Germany, it was legally never part of it. A number of the aforementioned city-states – though partly with altered borders – continue to exist as city-states within today's Federal Republic of Germany and today's Swiss Confederation (see "Cities that are component states of federations" below).
Among the most well-known periods of city-state culture in human history include ancient Greek city-states, and the merchant city-states of Renaissance Italy, who organised themselves in small independent centres. The success of small regional units coexisting as autonomous actors in loose geographical and cultural unity, as in Italy or Greece, often prevented their amalgamation into larger national units. However, such small political entities often survived only for short periods because they lacked the resources to defend themselves against incursions by larger states. Thus they inevitably gave way to larger organisations of society, including the empire and the nation state.
In Cyprus, the Phoenician settlement of Kition (in present-day Larnaca) was a city-state that existed from around 800 BC until the end of the 4th century BC.