Centralized Churches of Early Christianity
In patristic times, when basilicas ruled the earth, a few alternative church plans dotted the landscape. We may regard these designs as Stephen Jay Gould did the Burgess Shale fossils: novel forms that left no progeny. Nevertheless, both the churches and the fossils are beautiful and worthy of contemplation.
The longitudinal basilican church borrowed the shape of Roman law courts, markets, athletic facilities, and other public buildings. Centrally planned churches, by contrast, derive from Roman mausolea, imperial audience chambers, banqueting halls, and even garden pavilions. Central plans could be cruciform, round, polygonal, or polyconched and further enriched with ambulatories, galleries, and niches of varied shape. Constantine, that energetic patron of Christian architecture, built both types of churches and even mixed forms, such as in the basilican Church of the Nativity in Bethlehem with its octagonal headpiece covering the birthplace of Christ. Regardless of design, the main altar normally stood in the east of the building, not the center.
The old rule that basilicas were for community worship but other shapes were for honoring martyrs (martyria) is not universally true. Old St. Peter’s in Rome, built by Constantine, was one of the earliest basilican churches yet was sited over the Apostle’s grave and designed for the convenience of pilgrims. Meanwhile, Constantine’s Golden Octagon at Antioch was the city’s cathedral, not a martyr’s shrine.
The much imitated church that Constantine built to be his own burial place, Holy Apostles at Constantinople, was cruciform, with a central drum over the crossing where the emperor’s tomb lay within a circle of twelve piers representing the Apostles. St. Babylas near Antioch (380), the first martyrium built to enshrine translated relics, copied the cruciform shape and central burial spot of Holy Apostles. A contemporary martyrium designed by St. Gregory of Nyssa added hemispherical lobes (conches) between the arms of the cross and enclosed the structure within a square peristyle of forty columns. A century later, S. Stefano Rotundo in Rome has a circle-in cross-in circle plan: tall, cylindrical nave with an ambulatory attached to four rectangular chapels joined by covered porticoes.
A round design was even simpler. Around 350, Constantine built his daughter a domed and arcaded circular mausoleum, now called S. Costanza, against the wall of S. Agnese’s covered cemetery. The round footprint of St. John the Baptist in Gerasa (531) extrudes four small exedrae like pseudopods. So (contrary to Dan Brown’s allegations in The Da Vinci Code) circular churches existed before the Roman Pantheon, once a temple to all the gods, was rededicated to S. Maria ad Martyres in 610. There is nothing peculiarly pagan about roundness.
Only a single “working” church of tetraconch form still survives. San Lorenzo in Milan (378), a double-shelled quatrefoil with four square towers at the corners and three octagonal chapels budded off the curved exterior walls. Its original dome has been replaced by an octagonal baroque one. Tetraconch churches of the Middle East no longer exist.
But four lobes were not enough for St. Gereon in Cologne. This late fourth-century church was built with eight horseshoeshaped exedrae, a round apse, double-apsed narthex, and a huge atrium. Its mutant design left no progeny.
The most successful of the central plans was the polygon. And perhaps the oddest looking polygonal church was the early fifth century shrine of St. Philip at Hieropolis, which had a floor plan easily mistaken for an asterisk. Each side of its octagonal nave thrust out a barrel-vaulted rectangular niche, with tiny chapels of irregular shape hollowed out of the piers between each niche. The building was enclosed within a square of cells to house pilgrims.
Double-shelled octagons proved more popular. Although sloppily executed and noticeably askew, Justinian’s Church of H. Sergios and Bakchos (536) still stands under its pumpkin dome in Istanbul. But it has long been a mosque. The gem of the style is S. Vitale at Ravenna (547), where the octagonal core rises to a domed octagonal drum. The core is surrounded by seven semicircular niches (the eighth spot opens to the chancel), then enveloped by ambulatories and galleries to create an interior of harmonious complexity, glittering with mosaics and rich colored marbles.
The surviving beauties of S. Costanza, of S. Lorenzo, and of S. Vitale are living fossils, reminders of what might have been in church architecture.