Most assuredly, a city-state enjoys unconditional sovereignty, regulating its own taxes, has its own budget, and represents itself independently at the United Nations. However, the level of governance varies from one city-state to another.
The ancient Greece had various city-states that were sovereign. Other ancient city-states include Athens, Thebes, Corinth, Megara, Argos, and Sparta (Martin Web). Currently, the numbers of sovereign city-states is low and include Vatican City, Monaco, and Singapore. Indeed, Singapore was initially a member of the federal kingdom of Malaysia. However, it is now sovereign. Assuredly, Vatican City doubles as a city-state and the smallest country in the world since 1929. It entails the central city of Rome that equally serves as the headquarters of the Roman Catholic Church. Its president is the Pope (Parker 52-58). On the other hand, the boundary of Monaco doubles as the boundary of the city-state. Nevertheless, we have other city-states that are not sovereign. For example, Germany has three city-states that include Bremen, Berlin, and Hamburg (Parker 132-136). A mayor heads the three city-states. In addition, Austria has a federal state named, Vienna. The British colony of Gibraltar is also another city-state in the United Kingdom. In Pakistan, we have a city-state called the colony of .Gwadar City. Indeed, city-states fall under sovereign states, federally administered cities, cities that are component states of federations, and cities under international supervision like Danzig.
It is a hard fete to claim a country. Indeed, there is no universal way of claiming a country. However, according to the provisions of Article 1 of the Montevideo Convention on the Rights and Duties of States, a state should have mandatory four qualifications (The Globe and Mail Web).