Vatican City, is a country located within the city of Rome. With an area of approximately 44 hectares (110 acres), and a population of 1,000, it is the smallest state in the world by both area and population. However, formally it is not sovereign, with sovereignty being held by the Holy See.
It is an ecclesiastical or sacerdotal-monarchical state (a type of theocracy) ruled by the Bishop of Rome - the Pope. The highest state functionaries are all Catholic clergy of various national origins. Since the return of the Popes from Avignon in 1377, they have generally resided at the Apostolic Palace within what is now Vatican City, although at times residing instead in the Quirinal Palace in Rome or elsewhere.
Vatican City is distinct from the Holy See, which dates back to early Christianity and is the main episcopal see of 1.2 billion Latin and Eastern Catholic adherents around the globe. The independent city-state, on the other hand, came into existence in 1929 by the Lateran Treaty between the Holy See and Italy, which spoke of it as a new creation, not as a vestige of the much larger Papal States (756-1870), which had previously encompassed much of central Italy. According to the terms of the treaty, the Holy See has "full ownership, exclusive dominion, and sovereign authority and jurisdiction" over the city-state.
The name "Vatican" was already in use in the time of the Roman Republic for a marshy area on the west bank of the Tiber across from the city of Rome. Under the Roman Empire, many villas were constructed there, after Agrippina the Elder (14 BC - 18 October AD 33) drained the area and laid out her gardens in the early 1st century AD. In AD 40, her son, Emperor Caligula (31 August AD 12-24 January AD 41; r. 37-41) built in her gardens a circus for charioteers (AD 40) that was later completed by Nero.
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