The Vatican Apostolic Library, sometimes simply called the Vatican library, is home to a wide variety of biblical, theological and otherwise scholarly documents. From its conception, the library has specialized particularly in the storage and preservation of manuscripts, such as the 6th century Barberini Gospels and the 10th to 11th century Eastern Orthodox illumination, the Menologion of Basil II.
Among other manuscripts located at the Vatican library related to Christianity are the Gelasian Sacramentary, a book of liturgy, the Joshua Roll, another Byzantine illuminated manuscript, and the Vatican Croatian Prayer Book. Although much of the library's collection is religiously oriented, there are many secular works present as well, including a 5th century copy of Virgil's epic poem, the "Aeneid," and ancient copies of portions of Euclid's critical early work of geometry, "The Elements."
Although it is commonly associated with the Vatican library, the Vatican's secret archives are actually located elsewhere, being the central repository for all documents pertaining to Vatican officialdom and the acts of the Holy See. In addition to archives and state papers, the facility also houses various forms of written correspondence and the papal account books. While access to the archives' collections were either prohibited or extremely limited for centuries, they were finally opened to outsider researchers in 1881 by Pope Leo XIII. Among the most prized historical documents there are a letter of Mary Queen of Scots and the 1521 bull of excommunication for religious reformer, Martin Luther.