When was the Vatican established?
Vatican City
The Holy See dates back to early Christianity, and is the primate episcopal see of the Catholic Church, with 1.3billion Catholics around the world distributed in the Latin Church and 23 Eastern Catholic Churches. The independent Vatican City-state, on the other hand, came into existence in 11 February 1929 by the Lateran Treaty between the Holy See and Italy, which spoke of it as a new creation,[12] not as a vestige of the much larger Papal States (756–1870), which had previously encompassed much of central Italy.
Lateran Treaty
The agreements included a political treaty which created the state of the Vatican City and guaranteed full and independent sovereignty to the Holy See. The Pope was pledged to perpetual neutrality in international relations and to abstention from mediation in a controversy unless specifically requested by all parties. In the first article of the treaty, Italy reaffirmed the principle established in the 4 March 1848 Statute of the Kingdom of Italy, that "the Catholic, Apostolic and Roman Religion is the only religion of the State".[21] The attached financial agreement was accepted as settlement of all the claims of the Holy See against Italy arising from the loss of temporal power of the Papal States in 1870.