[30] Tacitus wrote that in AD 69, the Year of the Four Emperors, when the northern army that brought Vitellius to power arrived in Rome, "a large proportion camped in the unhealthy districts of the Vatican, which resulted in many deaths among the common soldiery; and the Tiber being close by, the inability of the Gauls and Germans to bear the heat and the consequent greed with which they drank from the stream weakened their bodies, which were already an easy prey to disease".

A shrine dedicated to the Phrygian goddess Cybele and her consort Attis remained active long after the ancient Basilica of St. Peter was built nearby.

They ruled the Papal States, which covered a large portion of the Italian peninsula, for more than a thousand years until the mid-19th century, when all the territory belonging to the papacy was seized by the newly created Kingdom of Italy.

They moved to the Quirinal Palace in 1583, after work on it was completed under Pope Paul V (1605–1621), but on the capture of Rome in 1870 retired to the Vatican, and what had been their residence became that of the King of Italy.

Thereafter, the popes resided undisturbed within the Vatican walls, and certain papal prerogatives were recognised by the Law of Guarantees, including the right to send and receive ambassadors.

[41] This situation was resolved on 11 February 1929, when the Lateran Treaty between the Holy See and the Kingdom of Italy was signed by Prime Minister and Head of Government Benito Mussolini on behalf of King Victor Emmanuel III and by Cardinal Secretary of State Pietro Gasparri for Pope Pius XI.

[24][20][42] The treaty, which became effective on 7 June 1929, established the independent state of Vatican City and reaffirmed the special status of Catholic Christianity in Italy.

[42] The Holy See, which governed the Vatican City, pursued a policy of neutrality during World War II under the leadership of Pope Pius XII.

Although German troops occupied Rome after the September 1943 Armistice of Cassibile, with Allied forces pushing them out in 1944, both sides respected the Vatican City's status as neutral territory.

In connection with the Allied invasion of Sicily, 500 United States Army Air Forces aircraft bombed Rome on 19 July 1943, targeting the city's railway hub in particular.

Approximately 1,500 people were killed, and Pius XII, who had been described in the previous month as "worried sick" about the possibility of Rome being bombed, toured the affected areas.

According to the Lateran Treaty, certain properties of the Holy See that are located in Italian territory, most notably the Papal Palace of Castel Gandolfo and the major basilicas, enjoy extraterritorial status similar to that of foreign embassies.

Some minor local features, principally mists and dews, are caused by the anomalous bulk of St Peter's Basilica, the elevation, the fountains, and the size of the large paved square.

[68] In 1279, Pope Nicholas III (Giovanni Gaetano Orsini, 1277–1280) moved his residence back to the Vatican from the Lateran Palace and enclosed this area with walls.

[69] The politics of Vatican City takes place in the context of an absolute elective monarchy and being governed by the Holy See, in which the head of the Catholic Church holds power.

The Pope exercises principal legislative, executive, and judicial power over the State of Vatican City, which is a rare case of a non-hereditary monarchy.

[70] The Holy See, which is distinct from Vatican City State, has permanent observer status, with all the rights of a full member except for a vote in the UN General Assembly.

But with the motu proprio Pontificalis Domus of 28 March 1968,[77] Pope Paul VI abolished the honorary positions that had continued to exist until then, such as Quartermaster general and Master of the Horse.

Acts of the commission must be approved by the Pope, through the Holy See's Secretariat of State[citation needed], and must be published in a special appendix of the Acta Apostolicae Sedis.

Vatican City has no armed forces of its own, although the Swiss Guard is a military corps of the Holy See responsible for the personal security of the Pope, and residents in the state.

[89][90] A large part of the historical documents of the very extensive Vatican Apostolic Archive is stored in the "Bunker", which was inaugurated in 1980, a two-storey reinforced concrete vault, under the Cortile della Pigna, equipped with systems for fire protection, climate and humidity control, and physical security.

It is responsible for fire fighting, as well as a range of civil defence scenarios including flood, natural disaster, and mass casualty incident.

Pope Francis also appointed an auditor-general authorized to carry out random audits of any agency at any time and engaged a US financial services company to review the Vatican's 19,000 accounts to ensure compliance with international money laundering practices.

The official websites of the Holy See[126] and of Vatican City[127] are primarily in Italian, with versions of their pages in a large number of languages to varying extents.

In statistics comparing countries in various per capita or per area metrics, Vatican City is often an outlier—these can stem from the state's small size and ecclesiastical function.

St. Peter's Basilica, designed by a succession of architects including Bramante, Michelangelo, Giacomo della Porta, Maderno and Bernini, is a renowned work of Renaissance architecture.

The Sistine Chapel is famous for its frescos, which include works by Perugino, Domenico Ghirlandaio and Botticelli, as well as the ceiling and Last Judgment by Michelangelo.

Among the academicians, there are or were the astrophysicist Martin John Rees, the mathematician Cédric Villani, the theoretical physicist Edward Witten, the Nobel Prize in Chemistry laureates Jennifer Doudna and Emmanuelle Charpentier, and Ernest Rutherford, the geneticists Luigi Luca Cavalli-Sforza and Francis Collins, the head transplant pioneer Robert J.

[137] The seat of the Pontifical Academy for Life, whose domains are bioethics and ethics of technology, is at San Callisto complex, a Vatican extraterritorial property.

In addition, it has contributed to philosophical interdisciplinary studies at the Center for Theology and the Natural Sciences in Berkeley, California and research on the history of astronomy thanks to its extensive library, which also includes a meteorite collection.