Catholic Encyclopedia (1913)/Baldachinum of the Altar
A dome-like canopy in wood, stone, or metal, erected over the high altar of larger churches, generally supported on four columns, though sometimes suspended by chains from the roof. Other forms will be noted in tracing the cause of its history. The name is late medieval, baldacchino, from Baldocco, Italian form of Bagdad whence came the precious cloths of which in their later development these canopies were made. It was called earlier ciborium, from the Greek kiborion (the globular seed-pod of the lotus, used as a drinking-cup) because of the similarity of its dome top to an inverted cup. The early history of the baldachinum is obscure, but it probably originated in the desire to give to the primitive altar table a more dignified and beautiful architectural setting. The arcosolium altars of the catacombs perhaps foreshadow this tendency. With the construction or adaptation of the larger church edifices of the fourth century, the baldachinum became their architectural centre, emphasizing the importance of the sacrificial table as the centre of Christian worship. Thus, while the altar retained its primitive simplicity of form and proportions, the baldachinum gave it the architectural importance which its surroundings demanded. By its dais-like effect, it designated the altar as a throne of honour. It served also the practical purpose of supporting, between its columns, the altar-curtains, while from its roof were suspended lamps, vases, richly ornamented crowns, and other altar decorations. The summit was surmounted by the altar-cross. The earliest reference to the baldachinum is found in the "Liber Pontificalis" (ed. Duchesne, I, 172, 191, 233, 235) which described the Fastidium argenteum given by Constantine to the Lateran basilica during the pontificate of Sylvester I (314-335) and replaced, after the ravages of Alaric's Gothic hordes, by another erected during the pontificate of Sixtus III (432- 440). The oldest representation in art is the early sixth-century mosaic in the church of St. George in Thessalonica; while the oldest actual specimen is that in the church of St. Apollinare in Classe at Ravenna (c. 810). The use of the baldachinum was general up to the twelfth century, when it yielded to the growing importance of the reliquary as an adjunct to the altar, sometimes disappearing altogether, sometimes taking the form of a canopy over the relic-casket. With the placing of the altar against the wall, the baldachinum took the form of a projecting dais canopy (v. Altar-Canopy under ALTAR: IN LITURGY) or became the ciborium-like superstructure of the tabernacle or central tower of the altar. Italy was less affected by this evolution than were the centres of Gothic art, and the use of the older form is common there to-day. The most magnificent baldachinum in the world is that in St. Peter's in Rome designed by Bernini for Pope Urban VIII.
John B. Peterson.