The church of the Gesù in Rome — officially the Church of the Most Holy Name of Jesus — is perhaps the most influential building in the history of Christian architecture after the Pantheon and St. Peter's. Not because it is the most beautiful. Not because it is the largest. But because it is the mother of a type: the single-hall plan with side chapels and transept, which becomes the model replicated thousands of times by Jesuit missions in South America, Asia, Africa, and the European cities of the Counter-Reformation. If you step into a Catholic church built between 1580 and 1780 anywhere in the world, it almost certainly has the plan of the Gesù.
The Jesuit program arises from the Counter-Reformation and the response to Protestantism. The Protestant church values preaching — the preacher's word explaining the Gospel to the assembled congregation. The Catholic response is: we preach too, and we do it better. The plan the Jesuits require for their church is a single hall, with no intermediate columns, where every worshipper sees the preacher and the altar. Length does not matter — what matters is width and an unobstructed view.
Vignola and the compromise
Cardinal Alessandro Farnese, who finances the construction, wants a church with side aisles — side aisles are the mark of a great church's dignity. The Jesuits want a single hall. Vignola resolves the conflict ingeniously: he builds a wide single nave, but along the sides he inserts a series of chapels — small rooms opening onto the central hall through arches. The chapels are not aisles — they are accessory spaces, not passable longitudinally. But visually, from outside, the church appears to have a lateral structure. The patron is satisfied. The Jesuits are satisfied. And Vignola has invented a type.
The façade is completed by Giacomo della Porta in 1584, after Vignola's death. The façade of the Gesù is itself a type — with volutes linking the upper part (the central nave, taller) to the lower part (the chapels, lower). The lateral volutes are an invention of Alberti for Santa Maria Novella in Florence (1470), taken up and systematized here, then replicated in thousands of Baroque and Neoclassical façades into the nineteenth century.
Vignola: the architect of treatises
Giacomo Barozzi da Vignola (1507–1573) is the most influential architect of the second half of the Roman Cinquecento — and the least celebrated relative to his historical weight. Trained in the circle of Raphael and Michelangelo, he becomes the reference point for the codification of the classical orders: his treatise "Regola delli cinque ordini d'architettura" (1562) is the most widely diffused manual of the classical orders in history, translated into every European language and used in schools of architecture into the nineteenth century. While Palladio writes a theoretical and narrative treatise, Vignola publishes graphic plates — measurements, proportions, details — with minimal text. Every architect in Europe knows Vignola's plates; many have never read Palladio in full.
But Vignola is also a practical and versatile architect: he builds Villa Farnese at Caprarola (1559), a pentagonal fortress transformed into a stately villa with a circular inner courtyard; he builds the Terme dei Papi in Viterbo; he collaborates with Michelangelo at St. Peter's before taking over its direction after the master's death. The Gesù is his last project, left unfinished at his death in 1573.
The Baroque interior and the global missions
The interior of the Gesù, sober at the time of construction, is transformed in the seventeenth century into a spectacle of marbles, stuccoes, frescoes and sculptures. The vault fresco cycle — the "Triumph of the Name of Jesus" by Giovanni Battista Gaulli, known as il Baciccia (1679) — is one of the most extreme examples of Baroque illusionistic painting: the painted figures "spill out" of the vault's frame and appear to stand out against the real sky. The distinction between architecture, painting and sculpture dissolves — the Baroque here reaches its fullest fusion of the arts. The Chapel of St. Ignatius (1696), with the silver statue of the Jesuits' founder and columns of lapis lazuli, is one of the most extravagant works of architectural goldsmithing in history.
The Jesuit typology is replicated in the missions adaptively: in China, the Jesuits use the spatial structure of the Gesù with Confucian decoration. In South America, with indigenous Guaraní decorations covering the Baroque façades of the missions in Paraguay and Argentina — one of the most extraordinary cases of architectural syncretism in colonial history. The typology serves as a universal structure; the cladding is local. Vignola's Gesù was born to resolve a conflict between patron and client — and ended up producing the most widespread building type across three continents for two hundred years.