ARCO TRIONFALE. — In Christian architecture, the triumphal arch is the great arch separating the central nave of the church from the presbytery, whether the latter includes the transept with the apse or the apse alone. In antiquity it often rose upon two great columns, but apart from this it was always distinguished by special ornaments, either sculptural, as in the basilicas of Syria, or mosaic, as in the great Roman basilicas.
Although the name triumphal arch is only of medieval usage (and is found especially in the lives of the Popes of the 8th–9th centuries in the Liber Pontificalis, where it is also called arcus maior), we must seek its very origin in the triumphal arches that Roman antiquity customarily erected for victorious emperors. Just as the ornamental reliefs of these arches recount the glories of heroes, so too the triumph of Christ is frequently represented on the triumphal arch of the Church. On the triumphal arch of Galla Placidia in S. Paolo fuori le Mura in Rome, we find the majestic bust of Christ above, surrounded by the four apocalyptic animals, while from the sides the twenty-four elders offer him their crowns. This apocalyptic triumph of Christ constitutes the preferred theme in the early Christian triumphal arch. At times, however, instead of the bust of Christ we find the lamb or the divine throne. Alongside this representation, Christ is also often shown seated upon the globe of the universe among apostles or saints, as, for example, at Parenzo, in S. Lorenzo fuori le Mura, and in S. Agata dei Goti in Rome.
In the Middle Ages, Christ’s triumph was represented on the triumphal arch in a manner certainly no less profound and expressive, namely by the so-called triumphal cross. At the beginning of the arch’s curve, the nave was crossed above by a great beam, upon which stood a monumental cross, often accompanied by the Madonna and S. Giovanni: a magnificent application of Venanzio Fortunato’s triumphal hymn for Good Friday, Vexilla regis prodeunt... Unfortunately, in later times this beautiful expression of the
Triumph of Christ was very often removed from churches, and thus, with the new forms of a new architecture, the ancient triumphal arch disappeared.