Pope Sixtus IV

Francesco della Rovere was born on 21 July 1414 in or near Celle Ligure, a coastal village close to Savona in the Republic of Genoa ^[1]. His family was of modest means, and later stories of noble ancestry appear to have been embellished after his election to the papacy. His father, Leonardo della Rovere, worked in the cloth trade, and the household had no obvious connection to the church hierarchy that Francesco would one day command ^[2].

As a boy he was placed with the Franciscan Order, reportedly after an illness during which his mother vowed him to Saint Francis. The friars educated him first at a convent near Savona, then sent him on for advanced study. He proved an unusually able student of philosophy and theology, attending the universities of Pavia, Bologna, and Padua, where he earned his doctorate in theology in 1444 ^[1].

The young friar built his early reputation in the lecture hall rather than the papal court. He taught at Padua, Bologna, Pavia, Siena, Florence, and Perugia, and his lectures attracted students who would themselves become prominent scholars ^[2]. His published theological works, including treatises on the Blood of Christ and on the power of God, circulated widely and marked him as one of the leading Franciscan minds of his generation ^[3].

Della Rovere's rise through the Franciscan Order was steady and earned. He served as procurator of the order in Rome and as provincial minister, and in 1464 the general chapter meeting in Perugia elected him minister general of the entire Franciscan Order ^[1]. In that office he pushed for stricter observance of the rule and worked to repair divisions within the order, gaining a reputation as a capable and honest administrator.

His abilities caught the attention of Pope Paul II, who created him a cardinal in September 1467 with the titular church of San Pietro in Vincoli ^[2]. As a cardinal he lived simply by the standards of the Roman court, kept up his scholarly output, and took part in the theological controversies of the day, including the long-running Franciscan and Dominican dispute over the Blood of Christ, on which he had written as a theologian.

When Paul II died suddenly in July 1471, the conclave that followed was short. On 9 August 1471 the cardinals elected della Rovere, and he took the name Sixtus IV ^[1]. Contemporary accounts suggest that promises of favors to key electors, arranged in part by his nephew Pietro Riario, smoothed the path to his election, a practice common in fifteenth century conclaves but one that foreshadowed the family favoritism of his reign ^[4].

The most visible of Pope Sixtus IV achievements is the Sistine Chapel, the great palace chapel he ordered built between 1473 and 1481 on the site of the older Cappella Magna ^[5]. He summoned the leading painters of central Italy, including Sandro Botticelli, Pietro Perugino, Domenico Ghirlandaio, and Cosimo Rosselli, to fresco its walls with parallel cycles from the lives of Moses and Christ. The chapel, later crowned by Michelangelo's ceiling under his nephew Julius II, remains the setting for papal conclaves to this day ^[5].

Sixtus rebuilt Rome on a scale no pope had attempted for generations. He widened and paved streets, restored the Aqua Virgo aqueduct to improve the city's water supply, and constructed the Ponte Sisto, the first new bridge across the Tiber since antiquity, completed for the jubilee year of 1475 ^[2]. He founded or refounded churches including Santa Maria del Popolo and Santa Maria della Pace, and his support for the Ospedale di Santo Spirito gave Rome one of the era's most advanced hospitals ^[6].

His patronage extended to learning and civic culture. In 1475 he formally established the Vatican Library as a public institution, appointing the humanist Bartolomeo Platina as its first librarian and greatly expanding its collections, a scene commemorated in a famous fresco by Melozzo da Forli ^[6]. In 1471 he donated a group of ancient bronzes, including the Capitoline Wolf, to the people of Rome, a gift usually counted as the founding act of the Capitoline Museums, often described as the oldest public museum collection in the world ^[7].

In church affairs he extended the feast of the Immaculate Conception of the Virgin Mary to the universal calendar in 1476, a cause dear to Franciscan theology, and he approved observances and offices connected with it ^[3]. He also annulled the surviving decrees of the Council of Constance that had asserted conciliar supremacy, strengthening papal authority against the conciliar movement ^[1].

For all his building and patronage, Sixtus IV governed as an Italian prince, and the harsher Pope Sixtus IV facts belong to this side of his reign. His nepotism was extreme even by Renaissance standards. He raised six of his nephews to the cardinalate, among them Giuliano della Rovere, the future Pope Julius II, and Pietro Riario, whose lavish spending scandalized Rome before his early death in 1474 ^[2]. Another nephew, Girolamo Riario, received the lordship of Imola, and the pope's efforts to carve out territories for his kinsmen drew the papacy deep into the wars of the Italian states ^[4].

The most notorious episode was the Pazzi conspiracy of 1478. Girolamo Riario, the Pazzi banking family, and Francesco Salviati, archbishop of Pisa, plotted to overthrow Medici rule in Florence. On 26 April 1478 assassins struck during Mass in the cathedral of Florence, killing Giuliano de' Medici and wounding his brother Lorenzo the Magnificent ^[4]. Sixtus had approved a change of regime while insisting, by his own account, that no one be killed. When Florence executed the conspirators, including the archbishop, the pope excommunicated Lorenzo, placed the city under interdict, and joined Naples in a two year war against Florence ^[4].

Other decisions cast long shadows. In 1478 Sixtus issued the bull that authorized Ferdinand and Isabella to appoint inquisitors in Castile, the founding act of the Spanish Inquisition, though he later protested against its severity and attempted, without success, to restrain its procedures ^[8]. In his final years he backed Venice in a war against Ferrara and then turned against his ally, placing Venice under interdict in 1483. The constant warfare drained the papal treasury and led to heavier taxation and the open sale of offices ^[1].

The final decade of the pontificate was dominated by war, diplomacy, and the ceaseless promotion of the della Rovere and Riario clans. The Ottoman capture of Otranto in southern Italy in 1480 briefly united the peninsula in alarm, and Sixtus contributed galleys and money to the campaign that recovered the city in 1481 after the death of Sultan Mehmed II ^[1]. His earlier attempt at a crusading fleet in 1472 had achieved little beyond raids on the Anatolian coast, and his repeated calls for a general crusade found few backers among the European powers ^[2].

At home he continued to build and to spend. Preparations for the jubilee of 1475 had already remade much of the city center, and work on churches, streets, and fortifications went on through his last years despite the strain on papal finances ^[6]. Chroniclers of the time noted the contrast between the splendor of Rome's new monuments and the exactions needed to pay for wars in the Romagna and against Ferrara.

Peace among the Italian states was finally arranged at Bagnolo in August 1484 on terms that disappointed the pope, since they left Venice holding gains he had opposed. Sixtus, already ill with gout and fever, is said by contemporaries to have been enraged by the news. He died in Rome on 12 August 1484, aged seventy, and was buried in Saint Peter's, where his bronze funerary monument, cast by Antonio del Pollaiuolo, is regarded as one of the masterpieces of fifteenth century sculpture ^[7].

Any balanced Pope Sixtus IV biography has to hold two reputations together. Historians credit him with turning Rome from a decayed medieval town into a true Renaissance capital: the Sistine Chapel, the Ponte Sisto, the refounded Vatican Library, and the Capitoline bronzes all survive as evidence of a pope who understood the power of art and scholarship ^[5]. Under his rule Rome drew painters, humanists, and builders whose work set the stage for the High Renaissance of the following decades ^[6].

The political ledger reads differently. His nepotism entrenched the practice of treating the Papal States as a family inheritance, his role in the Pazzi conspiracy stained the papacy's moral authority, and the bull enabling the Spanish Inquisition tied his name to an institution whose abuses he himself came to criticize ^[8]. Scholars such as Ludwig von Pastor, writing the standard history of the popes, judged him a ruler whose genuine piety and love of learning were repeatedly compromised by dynastic ambition ^[3].

His influence outlasted him through his family. His nephew Giuliano della Rovere became Pope Julius II in 1503 and completed much of what his uncle had begun, commissioning Michelangelo to paint the Sistine ceiling and launching the rebuilding of Saint Peter's ^[5]. The della Rovere oak tree in the chapel's decoration, the bridge that still carries his name across the Tiber, and the library he opened to scholars keep Sixtus IV woven into the daily fabric of Rome more than five centuries after his death ^[7].