The conch or semi-dome that covered the apse was always covered with mosaic pictures, usually paintings of our Lord, either seated or standing, with St Peter and St Paul, and other apostles and saints, on either hand. The beams of the roof were sometimes concealed by a flat ceiling, richly carved and gilt. The altar, standing in the centre of the chord of the apse on a raised platform reached by flights of steps, was rendered conspicuous by a lofty canopy supported by marble pillars (ciborium, baldacchino), from which depended curtains of the richest materials. Beneath the altar was the confessio, a subterranean chapel, containing the body of the patron saint, and relics of other holy persons. This was approached by descending flights of steps from the nave or aisles. The confessio in some cases reproduced the original place of interment of the patron saint, either in a catacomb-chapel or in an ordinary grave, and thus formed the sacred nucleus round which the church arose. We have good examples of this arrangement at St Peter's and St Paul's at Rome, and S. Apollinare in Classe, Ravenna. It was copied in the original cathedral of Canterbury. The bishop or officiating presbyter advanced from his seat in the centre of the semicircle of the apse to the altar, and celebrated the Eucharist with his face to the congregation below.
At the foot of the altar steps a raised platform, occupying the upper portion of the nave, formed a choir for the singers, readers and other inferior clergy. This oblong space was separated from the aisles and from the western portion of the nave by low marble walls or railings (cancelli). From these walls projected ambones or pulpits with desks, also of marble, ascended by steps.
The exterior of the basilicas was usually of an extreme plainness. The vast brick walls were unrelieved by ornament, save occasionally by arcading as at S. Apollinare in Classe, Ravenna, and had no compensating grace of outline or beauty of proportion. An exception was made for the entrance front, which was sometimes covered with plates of marble mosaics or painted stucco (Old St Peter's, S. Lorenzo). But in spite of any decorations the external effect of a basilica must always have been heavy and unattractive. S. Apollinare in Classe at Ravenna (fig. 8) affords a typical example. The campanile is a later addition. Within, apart from the beautiful mosaic decoration, a fine effect was produced by the arch of triumph and the apse, which terminated the nave and dominated the whole vast space of the interior.Fig. 9. - Façade of old St Peter's, Rome.
Fig. 10. - Ground-Plan of the original Basilica of St Peter's at Rome.
a, Porch. b, Atrium. c, Cloisters. d, Narthex. e, Nave. f, f, Aisles, g, Bema. h, Altar, protected by a double screen. i, Bishop's throne in centre of the apse. k, Sacristy. l, Tomb of Honorius. m, Church of St Andrew.
To pass from general description to individual churches, the first place must be given, as the earliest and grandest examples of the type, to the world-famous Roman basilicas; those of St Peter, St Paul and St John Lateran, "omnium urbis et orbis ecclesiarum mater et caput." It is true that no one of these exists in its original form, Old St Peter's having been entirely removed in the 16th century to make room for its magnificent successor; and both St Paul's and St John Lateran having been greatly injured by fire, and the last named being so completely modernized as to have lost all interest. Of the two former, however, we possess drawings and plans and minute descriptions, which give an accurate conception of the original buildings. To commence with St Peter's, from the illustrations annexed (figs. 9, 10, 11) it will be seen that the church was entered through a vast colonnaded atrium, 212 ft. by 235 ft., with a fountain in the centre, - the atrium being preceded by a porch mounted by a noble flight of steps. The church was 212 ft. wide by 380 ft. long; the nave, 80 ft. in width, was six steps lower than the side aisles, of which there were two on each side. The four dividing colonnades were each of twenty-two Corinthian columns. Those next the nave supported horizontal entablatures.
The inner colonnades bore arches, with a second clerestory. The main clerestory walls were divided into two rows of square panels containing mosaics, and had windows above. The transept projected beyond the body of the church, - a very unusual arrangement. The apse, of remarkably small dimensions, was screened off by a double row of twelve wreathed columns of Parian marble. The pontifical chair was placed in the centre of the curve of the apse, on a platform raised several steps above the presbytery. To the right and left the seats of the cardinals followed the line of the apse. At the centre of the chord stood the high altar beneath a ciborium, resting on four pillars of porphyry. Beneath the altar was the subterranean chapel, the centre of the devotion of so large a portion of the Christian world, believed to contain the remains of St Peter; a vaulted crypt ran round the foundation wall of the apse in which many of the popes were buried. The roof showed its naked beams and rafters.
Fig. 11. - Sectional view of the old Basilica of St Peter, before its destruction in the 16th century.
Fig. 12. - Ground-Plan of St Paul's, Rome, before its destruction by fire.
a, Narthex. b, Nave. c, c, Side aisles. d, Altar. e, Bema. f, Apse.