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 Library
The Vatican Secret Archives, located in Vatican City, is the central archive for all of the acts promulgated by the Holy See, as well as the state papers, correspondence, papal account books, and many other documents which the church has accumulated over the centuries. In the 17th century, under the orders of Pope Paul V, the Secret Archives were separated from the Vatican Library, where scholars had some very limited access to them, and remained absolutely closed to outsiders until 1881, when Pope Leo XIII opened them to researchers, more than a thousand of whom now examine its documents each year.