Vatican Library
The Vatican Apostolic Library (Latin: Bibliotheca Apostolica Vaticana, Italian: Biblioteca Apostolica Vaticana), more commonly known as the Vatican Library or informally as the Vat, is the library of the Holy See, located in Vatican City, and is the city-state's national library. It was formally established by Pope Sixtus IV on June 15, 1475, by the papal bull Ad decorem militantis ecclesiae, although it is much older.