San Paolo fuori la Mura (St. Paul’s outside the Walls)

Perhaps the most demanding question that can be asked of any architect is to invent a building to suit a new purpose, and the provision of an adequate, even seemly, answer is indeed an architectural feat. From the beginning of the fourth century a.d., congregational worship by large numbers of people needed a hall, and the Roman basilica—a civil law court—became one model for churches in western Europe. The early Christian architects ingeniously combined the vast, articulated open spaces of the basilica with the familiar layout of the Roman domus to produce a new architectural type: the basilican church. San Paolo fuori la Mura, begun soon after 314 and completed in the thirteenth century, although completely rebuilt after 1823, is the clearest example, simply because the others have been “modernized” over the years.

The first 250 years of Christianity were marked by intermittent brutal persecution, so the places where the faithful gathered were necessarily unobtrusive. At first the religion generated no specific architectural forms, its underground congregations meeting in larger houses (domus) or even literally underground in the catacombs near Rome. In a.d. 313 the Edict of Toleration granted legal recognition to Christianity and the emperor Constantine initiated a program to build meeting places for the emancipated believers. The church leaders and their architects had a problem: was there an appropriate form for a building whose God did not “dwell in temples made with hands”? For associative reasons, pagan temples provided an inappropriate precedent; neither did their spatial organization suit the church’s developing liturgy.

The plan of the first basilican churches reflected the social organization of the domus, creating a house for the family of God. And in terms of a gathering place to worship the King of Kings, what could surpass the basilica—from the Greek word for royalty? The standard plan, linear in every respect, included an atrium, or forecourt; a narthex, or porch; and a long nave flanked by single or double side aisles. Every feature of construction and decoration drew the worshiper’s eye immediately to the altar in a polygonal or semicircular apse at the eastern end. The space was achieved with the simplest and lightest of structural systems: slender parallel walls, either solid from the ground or carried above lofty arcades, supported trussed timber roofs (usually obscured by a coffered ceiling). Avoiding the need to cope with lateral thrusts, the architects created vast ethereal spaces that still provoke admiration, even awe.

In Rome the established Christian foci—often the sites of martyrdoms—became the locations of these huge basilicas: San Giovanni in Laterano (311–314), San Pietro (begun 324), Santa Maria Maggiore (432–440), and San Paolo fuori la Mura. Between the nave and the apse each had a short transept, an oblong hall crossing the nave to form a T-shaped cross. Typically, columns, marble panels, dressed masonry, and even roof tiles from pagan temples were used as instant building materials. Many smaller basilicas were built, such as Santa Sabina, Rome, and Sant’ Apollinare in Classe, Ravenna, both of the fifth century.

Tradition has it that the apostle Paul was executed in Rome between a.d. 64 and 68 and that his tomb in the Via Ostia was conserved by a woman named Lucina who owned the surrounding land. There may have been an oratory on the site as early as 103, and the place was certainly marked by a cella memoriœ at the beginning of the third century. Around 314 Constantine had transformed it into the basilica that was rebuilt and enlarged in 386 by the Consul Sallustrius on the orders of the emperors Valentinian, Theodosius, and Arcadius. The mosaic decoration was completed under Honorius and Theodosius’s daughter, Galla Placidia. The church of San Paolo fuori la Mura reached its height from the thirteenth century onward.

The medieval worshiper would have approached across the atrium, seeing the magnificent color of Pietro Cavallini’s mosaics on the west facade. The eleventh-century bronze doors were made in Constantinople by Staurakios of Chios for Hildebrand; inlaid with niello work, they portrayed saints and martyrs. Once inside, the vast space—nearly 440 feet long by 217 feet wide (132 by 65 meters), with a coffered ceiling 100 feet (30 meters) above the marble floor—would have been seen, but hardly taken in, all at once. Eighty fluted columns of pavonazzetto and Parian marble divided the 82-foot-wide (24.6-meter) nave from the flanking double aisles. Twenty-four of them were perfectly matched; the remainder came from various pagan temples. High on the nave walls panels were decorated with frescoes of the lives of St. Peter and St. Paul and other biblical subjects; below them and above the arcades, mosaic portraits of the popes led the eye inexorably to the east end. There, a huge triumphal arch, with scintillating gold and colored mosaics of biblical subjects, was carried on two 50-foot (15-meter) marble Ionic columns. Framed by the arch, the tomb of St. Paul (1285) stands under a Gothic baldachin by Arnolfo di Cambio; behind it, the apse was “all aglow with mosaic.” San Paolo fuori la Mura was a glorious, wondrous space.
The building has had a checkered history. There have been damaging earthquakes and simple neglect when the area near the Tiber became malarial. Because it was outside the walls it was exposed to invaders: the Langobards plundered it in 739 and Saracens in 847, leading Pope John VIII belatedly to build a citadel in 872. Through all this, it preserved its original character and form more than any church in Rome for nearly 1,500 years. It was almost totally destroyed by fire in July 1823 through the carelessness of a workman. The whole world, Catholic and non-Catholic alike, contributed to its restoration by the architect Luigi Poletti; for example, the Khedive of Egypt sent pillars of alabaster, and the Tsar of Russia gave malachite and lapis lazuli for the tabernacle. San Paolo fuori la Mura was reconsecrated in December 1854. As it stands today, the church articulates by its structure the brilliance of the early Christian architects.