Pope Sixtus IV (: 21 July 1414 – 12 August 1484), born Francesco della Rovere, was head of the Catholic Church and ruler of the Papal States from 9 August 1471 to his death in August 1484. His accomplishments as pope included the construction of the Sistine Chapel and the creation of the Vatican Library. A patron of the arts, he brought together the group of artists who ushered the Early Renaissance into Rome with the first masterpieces of the city's new artistic age. Sixtus founded the Spanish Inquisition through the bull Exigit sincerae devotionis affectus (1478), and he annulled the decrees of the Council of Constance. He was noted for his nepotism and was personally involved in the infamous Pazzi conspiracy. Early life Francesco was born to a family of modest means from Liguria, Italy, the son of Leonardo della Rovere and Luchina Monleoni. He was born in Celle Ligure, a town near Savona. As a young man, Della Rovere joined the Franciscan Order, an unlikely choice for a political career, and his intellectual qualities were revealed while he was studying philosophy and theology at the University of Pavia. He went on to lecture at Padua and many other Italian universities. In 1464, Della Rovere was elected Minister General of the Franciscan order at the age of 50. In 1467, he was appointed Cardinal by Pope Paul II with the titular church being the Basilica of San Pietro in Vincoli. Before his papal election, Cardinal della Rovere was renowned for his unworldliness and had written learned treatises, including On the Blood of Christ and On the Power of God. His reputation for piety was one of the deciding factors that prompted the College of Cardinals to elect him Pope upon the unexpected death of Paul II at the age of fifty-four. Papacy Upon being elected Pope, Della Rovere adopted the name Sixtus, which had not been used since the 5th century. One of his first acts was to declare a renewed crusade against the Ottoman Turks in Smyrna. However, after the conquest of Smyrna, the fleet disbanded. Some fruitless attempts were made towards unification with the Greek Church. For the remainder of his pontificate, Sixtus turned to temporal issues and dynastic considerations. Nepotism Sixtus IV sought to strengthen his position by surrounding himself with relatives and friends. In the fresco by Melozzo da Forlì, he is accompanied by his