he east, and the altar at the west end, so that the celebrant
faced the congregation during the divine office. (2) The church was
approached through a cloistered _atrium_ or fore-court, in the middle of
which was a fountain, the place of purification for those intending to
enter the church. (3) At the west end of the cloister three doorways
opened into the nave of the church, and one on either side into the
side aisles. (4) The nave communicated with the aisles by a row of
columns beneath an entablature: there were also outer aisles,
communicating with the inner by columns bearing rounded arches. (5) The
side walls of the nave, above the entablature, were not pierced for
galleries, but were covered by two rows of mosaic pictures, one above
the other, on each side, the upper row corresponding to the height of
the space between the outer and inner roofs of the aisle. Above this,
the walls rose into a clerestory, pierced with round-headed windows at
regular intervals; and a high entablature supported the great tie-beams
of the wooden roof. (6) The quire of singers, divided from the rest of
the church by low screen walls, probably occupied the centre of the
western portion of the nave. (7) A tall open arch divided the nave from
the transept, which was of equal height with the nave, and projected
south and north as far as the walls of the outer aisles. Here probably
were places reserved for distinguished persons, near the platform of the
altar. (8) West of the transept, entered by a tall and wide arch, was
the apse. Beneath the arch was a screen, formed by a row of columns,
under an entablature which bore statues of our Lord and the apostles:
this crossed the arch at the foot of the steps leading to the altar and
seats of the clergy. (9) Beneath the altar platform, and entered by
doorways on each side of the flight of steps, was the crypt or
_confessio_, the traditional place of martyrdom of St Peter, and the
resort of pilgrims to the tomb of the apostles. The hallowed place was
immediately beneath the altar.

Sec. 5. The sixth century basilicas of Ravenna, Sant' Apollinare in Classe
and Sant' Apollinare Nuovo, differ in plan from the Roman basilicas (1)
in the fact that they have always had the altar at the east, and the
entrance at the west end; (2) by substituting, for a colonnaded atrium,
a closed porch or _narthex_ in front of the entrance of the building. In
process of time, two of the greater Roman basilicas, San Paolo