ilica churches. The seat of the president became the
bishop's throne, the seats for assessors were appropriated to the
clergy, and the altar retained substantially its old position in front
of the apse, generally with a canopy erected over it. This disposition
continues in basilica churches to the present day. At St. Peter's in
Rome, for example, the Pope occupies a throne in the middle of the
apse, and says mass with his face turned towards the congregation at
the high altar, which stands in front of his throne under a vast
baldacchino or canopy; but in Western Christendom generally a change
has been made,--the altar has been placed in the apse where the
bishop's throne formerly stood, and the throne of the bishop and
stalls of his clergy have been displaced, and are to be found at the
sides of the choir or presbytery.

[Illustration: FIG. 157.--SANT' APOLLINARE, RAVENNA. PART OF THE
ARCADE AND APSE.]

Many basilica churches were erected out of fragments taken from older
buildings, and present a curious mixture of columns, capitals, &c.;
others, especially those at Ravenna, exhibit more care, and are noble
specimens of ancient and severe architectural work. The illustration
which we give of part of the nave, arcade, and apse of one of these,
Sant' Apollinare in Classe, shows the dignified yet ornate aspect of
one of the most carefully executed of these buildings (Fig. 157).

In some of these churches the decorations are chiefly in mosaic, and
are extremely striking. Our illustration of the apse of the great
basilica of St. Paul without the walls (Fig. 158) may be taken as a
fair specimen of the general arrangement and treatment of the crowd of
sacred figures and subjects which it is customary to represent in
these situations; but it can of course convey no idea of the brilliant
effect produced by powerful colouring executed in mosaic, the most
luminous of all methods of enrichment. The floor of most of them was
formed in the style of mosaic known as "opus Alexandrinum," and the
large sweeping, curved bands of coloured material with which the main
outlines of the patterns are defined, and the general harmony of
colour among the porphyries and other hard stones with which these
pavements were executed, combine to satisfy the eye. A splendid
specimen of opus Alexandrinum, the finest north of the Alps, exists in
the presbytery of Westminster Abbey.

[Illustration: FIG. 158.--APSE OF THE BASILICA OF ST. PAUL W