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.
Holy See
Notwithstanding, the Holy See was represented in and identified as a "permanent subject of general customary international law vis-à-vis all states" in the Congress of Vienna of 1814 to 1815. The Papal States were recognised under the rule of the Papacy and largely restored to their former extent. Despite the Capture of Rome in 1870 by the Kingdom of Italy and the Roman Question during the Savoyard era (which made the Pope a "prisoner in the Vatican" from 1870 to 1929), its international legal subject was "constituted by the ongoing reciprocity of diplomatic relationships" that not only were maintained but multiplied.