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.
Vatican Hill
The Vatican Hill was included within the city limits of Rome during the reign of Pope Leo IV, who, between 848 and 852, expanded the city walls to protect St. Peter's Basilica and the Vatican. Thus, Vatican Hill has been within the walls and city limits of Rome for over 1100 years. Until the Lateran Treaties in 1929 it was part of the Rione of Borgo.