"The most imposing Italian palace of the sixteenth century", according to Sir Banister Fletcher (1), this palace was designed by Antonio da Sangallo the Younger (1484-1546), one of Bramante's assistants in the design of St. Peter's. Construction began in 1515 after one or two years of preparation, commissioned by Alessandro Farnese, who had been appointed as a Cardinal in 1493 at age 25 (thanks to his sister, who was Pope Alexander VI Borgia's official mistress) and was living a princely lifestyle. Work was interrupted by the Sack of Rome in 1527. When in January 1534 Cardinal Alessandro was made pope, as Paul III, he employed Michelangelo to complete the third story with its deep cornice and revise the courtyard, as an emblematic "power house" suitable to the Farnese family. The massive facade dominates a small piazza; the memorable features of its facade are the alternating pediments that cap the windows of the piano nobile, the central rusticated portal and Michelangelo's projecting cornice. The central window Michelangelo revised when the cardinal became pope, adding an architrave to support the largest coat-of-arms with papal tiara Rome had ever seen. When Paul stepped to the balcony, the entire facade became a setting for his person. The courtyard, initially open arcades, is ringed by an academic exercise in ascending orders (Doric, Corinthian, and Ionic). The piano nobile was garlanded by Michelangelo.
The palazzo was redesigned in 1534 and 1541, modified under Michelangelo after Sangallo's death in 1546 onwards, adjusted for the papal nephew Ranuccio Farnese by Vignola and completed by Giacomo della Porta's porticoed facade towards the Tiber, for the second cardinal Alessandro Farnese, finished in 1589. Several main rooms were frescoed with elaborate allegorical programs including a series of frescoes on Hercules, and The Loves of the Gods by Annibale Carracci and other artists, 1597-1608. For generations the room with Herculean frescoes (Sala d'Ercole) housed the famous sculpture from Greco-Roman antiquity known as the Farnese Hercules. Other works from the family collection of classical sculpture were also housed in the Palazzo.
On the garden side, which faces the Tiber, Michelangelo proposed to give the palazzo's vast bulk some breathing room with a bridge across Via Giulia (completed) to link the center of the garden facade with the Pope's villa, the Villa Farnesina on the Trastevere side. In piazza Farnese, the "urban" face of the palazzo, two granite basins came in the sixteenth century from the Baths of Caracalla.
Following the death of Odoardo Cardinal Farnese in 1626, the palazzo stood virtually uninhabited for twenty years. At the conclusion of the War of Castro with the papacy, Duke Odoardo was able to regain his family properties, which had been sequestered. The resulting inventory (see below) is the oldest surviving complete inventory of Palazzo Farnese. After Odoardo's death, Pope Alexander VII allowed Queen Christina of Sweden to lodge in the palace for several months, but she "proved a tenant from hell". After her departure for Paris, the papal authorities discovered that her unruly servants not only had stolen the silver, tapestries, and paintings, but also had "smashed up doors for firewood" and removed sections of copper roofing.
In Puccini's opera Tosca (1900), set in Napoleonic Rome, the heroine's confrontation with the malevolent Chief of Police, Scarpia, takes place in Palazzo Farnese. The Palazzo was inherited from the Farnese by the Bourbon kings of Naples, from whom the French government purchased it in 1874. Though the government of Mussolini ransomed it in 1936, the French Embassy remains, under a 99-year lease for which they pay the Italian Government a symbolic fee of 1 euro per month.
The Palazzo Farnese houses the great scholarly library amassed by the Ecole Française de Rome, concentrating especially on the archeology of Italy and medieval Papal history. The Ecole Française de Rome embarked on a massive project of publishing as much of the documentation of the constructing of the palazzo, its frescoes and furnishings, library and works of art, fully annotated and indexed. The first three volumes are:
The Palazzo's design has been mimicked in several buildings outside Italy, including the Château Grimaldi near Aix-en-Provence, the National Building Museum in Washington, D.C. and the Chief Secretary’s Building in Sydney.