Holy See
Although the Holy See is sometimes metonymically referred to as the "Vatican", the Vatican City State was distinctively established with the Lateran Treaty (1929) between the Holy See and Italy to ensure the temporal, diplomatic, and spiritual independence of the Papacy. As such, ambassadors are officially accredited to the Holy See and not the Vatican City State. Conversely, Papal nuncios to states and international organisations are recognised as representing the Holy See and the integrity of the Catholic Church along with its 1.3 billion members, not the Vatican City State, as prescribed also in the Canon law of the Catholic Church (1983). The "Holy See" thus refers to the See of Rome viewed as the central government of the Catholic Church. The Catholic Church, in turn, is the largest non-government provider of education and health care in the world, while the diplomatic status of the Holy See facilitates the access of its vast international network of charities.
Catholic Church
The Italian unification of the 1860s incorporated the Papal States, including Rome itself from 1870, into the Kingdom of Italy, thus ending the papacy's millennial temporal power. In response, Pope Pius IX excommunicated King Victor Emmanuel II, refused payment for the land, and rejected the Italian Law of Guarantees, which granted him special privileges. To avoid placing himself in visible subjection to the Italian authorities remained a "prisoner in the Vatican". This stand-off, which was spoken of as the "Roman Question", was resolved by the 1929 Lateran Treaties, whereby the Holy See acknowledged Italian sovereignty over the former Papal States in return for payment and Italy's recognition of papal sovereignty over Vatican City as a new sovereign and independent state.