Pope Sixtus IV in the context of "Sistine Chapel ceiling"

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. It is one of the oldest libraries in the world and contains one of the most significant collections of historical texts. It has 75,000 codices from throughout history, as well as 1.1 million printed books, which include some 8,500 incunabula.

The Vatican Library is a research library for history, law, philosophy, science, and theology. The Vatican Library is open to anyone who can document their qualifications and research needs. Photocopies for private study of pages from books published between 1801 and 1990 can be requested in person or by mail.

The Sistine Chapel (/ˈsɪstiːn/ SIST-een; Latin: Sacellum Sixtinum; Italian: Cappella Sistina [kapˈpɛlla siˈstiːna]) is a chapel in the Apostolic Palace, the pope's official residence in Vatican City. Originally known as the Cappella Magna ('Great Chapel'), it takes its name from Pope Sixtus IV, who had it built between 1473 and 1481. Since that time, it has served as a place of both religious and functionary papal activity. Today, it is the site of the papal conclave, the process by which a new pope is selected. The chapel's fame lies mainly in the frescoes that decorate its interior, most particularly the Sistine Chapel ceiling and The Last Judgment, both by Michelangelo.

During the reign of Sixtus IV, a team of Renaissance painters including Sandro Botticelli, Pietro Perugino, Pinturicchio, Domenico Ghirlandaio and Cosimo Rosselli, created a series of frescoes depicting the Life of Moses and the Life of Christ, offset by papal portraits above and trompe-l'œil drapery below. They were completed in 1482, and on 15 August 1483 Sixtus IV celebrated the first mass in the Sistine Chapel for the Feast of the Assumption, during which the chapel was consecrated and dedicated to the Virgin Mary.

Lorenzo di Piero de' Medici (Italian: [loˈrɛntso de ˈmɛːditʃi]), known as Lorenzo the Magnificent (Italian: Lorenzo il Magnifico; 1 January 1449 – 8 April 1492), was an Italian statesman, the de facto ruler of the Florentine Republic, and the most powerful patron of Renaissance culture in Italy. Lorenzo held the balance of power within the Italic League, an alliance of states that stabilized political conditions on the Italian Peninsula for decades, and his life coincided with the mature phase of the Italian Renaissance and the golden age of Florence. As a patron, he is best known for his sponsorship of artists such as Botticelli and Michelangelo. On the foreign policy front, Lorenzo manifested a clear plan to stem the territorial ambitions of Pope Sixtus IV, in the name of the balance of the Italic League of 1454. For these reasons, Lorenzo was the subject of the Pazzi conspiracy (1478), in which his brother Giuliano was assassinated. The Peace of Lodi of 1454 that he supported among the various Italian states collapsed with his death. He is buried in the Medici Chapel in Florence.

Bonaventure OFM (/ˈbɒnəvɛntʃər, ˌbɒnəˈvɛntʃər/ BON-ə-ven-chər, -⁠VEN-; Italian: Bonaventura da Bagnoregio [ˌbɔnavenˈtuːra da (b)baɲɲoˈrɛːdʒo]; Latin: Bonaventura de Balneoregio; born Giovanni di Fidanza; 1221 – 15 July 1274) was an Italian Catholic Franciscan bishop, cardinal, scholastic theologian and philosopher.

The seventh Minister General of the Order of Friars Minor, he also served for a time as Bishop of Albano. He was canonised on 14 April 1482 by Pope Sixtus IV and declared a Doctor of the Church in 1588 by Pope Sixtus V, becoming known as the "Seraphic Doctor" (Latin: Doctor Seraphicus). His feast day is 15 July.