Vatican city

State of the Vatican City, is a landlocked sovereign city-state whose territory consists of a walled enclave within the city of Rome, the capital city of Italy. It has an area of approximately 44 hectares (110 acres) (0.44 km2), and a population of just over 800.[5][12]
Vatican City is a city-state that came into existence in 1929. It is distinct from the Holy See, which dates back to early Christianity and is the main episcopal see of 1.147 billion Latin and Eastern Catholic adherents around the globe. Ordinances of Vatican City are published in Italian; official documents of the Holy See are issued mainly in Latin. The two entities even have distinct passports: the Holy See, not being a country, only issues diplomatic and service passports; the state of Vatican City issues normal passports. In both cases the passports issued are very few.
The Lateran Treaty in 1929, which brought the city-state into existence, spoke of it as a new creation (Preamble and Article III), not as a vestige of the much larger Papal States (756-1870) that had previously encompassed central Italy. Most of this territory was absorbed into the Kingdom of Italy in 1860, and the final portion, namely the city of Rome with a small area close to it, ten years later, in 1870.
Vatican City is an ecclesiastical or sacerdotal-monarchical state, ruled by the bishop of Rome—the Pope. The highest state functionaries are all Catholic clergymen of various nationalities. It is the sovereign territory of the Holy See (Sancta Sedes) and the location of the Pope's residence, referred to as the Apostolic Palace.
The Popes have resided in the area that in 1929 became Vatican City since the return from Avignon in 1377. Previously, they resided in the Lateran Palace on the Caelian Hill on the opposite side of Rome, which site Constantine gave to Pope Miltiades in 313. The signing of the agreements that established the new state took place in the latter building, giving rise to the name of Lateran Pacts, by which they are known.
The name "Vatican" is ancient and predates Christianity, coming from the Latin Mons Vaticanus, meaning Vatican Mount. The territory of Vatican City is part of the Mons Vaticanus, and of the adjacent former Vatican Fields where St. Peter's Basilica, the Apostolic Palace, the Sistine Chapel, and museums were built, along with various other buildings. The area was part of the Roman rione of Borgo until 1929. Being separated from the city, on the west bank of the Tiber river, the area was an outcrop of the city that was protected by being included within the walls of Leo IV (847–55), and later expanded by the current fortification walls, built under Paul III (1534–49), Pius IV (1559–65) and Urban VIII (1623–44). When the Lateran Treaty of 1929 that gave the state its present form was being prepared, the boundaries of the proposed territory were influenced by the fact that much of it was all but enclosed by this loop. For some tracts of the frontier, there was no wall, but the line of certain buildings supplied part of the boundary, and for a small part of the frontier a modern wall was constructed. The territory includes St. Peter's Square, distinguished from the territory of Italy only by a white line along the limit of the square, where it touches Piazza Pio XII. St. Peter's Square is reached through the Via della Conciliazione which runs from the Tiber River to St. Peter's. This grand approach was constructed by Benito Mussolini after the conclusion of the Lateran Treaty.
According to the Lateran Treaty, certain properties of the Holy See that are located in Italian territory, most notably Castel Gandolfo and the major basilicas, enjoy extraterritorial status similar to that of foreign embassies. These properties, scattered all over Rome and Italy, house essential offices and institutions necessary to the character and mission of the Holy See.
Castel Gandolfo and the named basilicas are patrolled internally by police agents of Vatican City State and not by Italian police. St. Peter's Square is ordinarily policed jointly by both.

In this originally uninhabited area (the ager vaticanus) on the opposite side of the Tiber from the city of Rome, Agrippina the Elder (14 BC – 18 October AD 33) drained the hill and environs and built her gardens in the early 1st century AD. Emperor Caligula (37-41) started construction of a circus (AD 40) that was later completed by Nero, the Circus Gaii et Neronis, usually called, simply, the Circus of Nero. The Vatican obelisk was originally taken by Caligula from Heliopolis, Egypt to decorate the spina of his circus and is thus its last visible remnant. This area became the site of martyrdom of many Christians after the Great Fire of Rome in AD 64. Ancient tradition holds that it was in this circus that Saint Peter was crucified upside down. Opposite the circus was a cemetery separated by the Via Cornelia. Funeral monuments and mausoleums and small tombs as well as altars to pagan gods of all kinds of polytheistic religions were constructed lasting until before the construction of the Constantinian Basilica of St. Peter's in the first half of the 4th century. Remains of this ancient necropolis were brought to light sporadically during renovations by various popes throughout the centuries increasing in frequency during the Renaissance until it was systematically excavated by orders of Pope Pius XII from 1939 to 1941.
In 326, the first church, the Constantinian basilica, was built over the site that early Roman Catholic apologists (from the first century on) as well as noted Italian archaeologists argue was the tomb of Saint Peter, buried in a common cemetery on the spot. From then on the area started to become more populated, but mostly only by dwelling houses connected with the activity of St. Peter's. A palace was constructed near the site of the basilica as early as the 5th century during the pontificate of Pope Symmachus (reigned 498–514)
Popes in their secular role gradually came to govern neighbouring regions and, through the Papal States, ruled a large portion of the Italian peninsula for more than a thousand years until the mid 19th century, when all of the territory of the Papal States was seized by the newly created Kingdom of Italy. For much of this time the Vatican was not the habitual residence of the Popes, but rather the Lateran Palace, and in recent centuries, the Quirinal Palace, while the residence from 1309–77 was at Avignon in France.
In 1870, the Pope's holdings were left in an uncertain situation when Rome itself was annexed by the Piedmont-led forces which had united the rest of Italy, after a nominal resistance by the papal forces. Between 1861 and 1929 the status of the Pope was referred to as the "Roman Question". They were undisturbed in their palace, and given certain recognitions by the Law of Guarantees, including the right to send and receive ambassadors. But they did not recognize the Italian king's right to rule in Rome, and they refused to leave the Vatican compound until the dispute was resolved in 1929. Other states continued to maintain international recognition of the Holy See as a sovereign entity. In practice Italy made no attempt to interfere with the Holy See within the Vatican walls. However, they confiscated church property in many other places, including, perhaps most notably, the Quirinal Palace, formerly the pope's official residence. Pope Pius IX (1846–78), the last ruler of the Papal States, claimed that after Rome was annexed he was a "Prisoner in the Vatican". This situation was resolved on 11 February 1929 between the Holy See and the Kingdom of Italy.
The treaty was signed by Benito Mussolini on behalf of King Victor Emmanuel III and by Cardinal Secretary of State Pietro Gasparri for Pope Pius XI. The Lateran Treaty and the Concordat established the independent State of the Vatican City and granted Roman Catholicism special status in Italy. In 1984, a new concordat between the Holy See and Italy modified certain provisions of the earlier treaty, including the position of Roman Catholicism as the Italian state religion.