TWILIGHT AND DAWN PROM THE <5TH TO THE  IOTH CENTURY
scholce, or the private halls in large houses and palaces (for instance,
that of the Flavian emperors on the Palatine (fig. 3))—smaller apsed
rooms, which may indeed have been used for private worship by
Christians.
But since 1917 we know of a much more direct connection between
Christian and Pagan religious architecture. The so-called Basilica
of Porta Maggiore (fig. 4) is a little subterranean building of only
about forty feet length. With its nave and aisles, its piers and apse it
looks exactly like a Christian chapel Stucco reliefs reveal that it was
the meeting-place of one of the many mystical sects which had come
to Rome from the East, before and after the advent of die sect of the
Christians. It is attributed to the ist century a.d. Considering the
close dependence of Early Christian thought on that of the other
oriental religions believing in a saviour, in sacrifice and re-birth, the
basilica of Porta Maggiore is the most convincing single source of
Early Christian architecture yet found.
During the 4th century Constantine and his successors built vast
basilicas in East and West; by the 5th century Christian churches
existed everywhere—even in England (Silchcster). Most of them
are varieties of the basilican plan. An exception were baptisteries and
memorials or mausoleum chapels for which, on a Roman precedent,
centrally planned buildings were preferred. On a large scale central
planning was developed chiefly in Byzantium itself. It culminated
in Justinian's two large churches, St. Scrgius and Bacchus and then
St, Sophia (532-37). On Italian soil a reflection of these, and a res-
plendent one indeed, is found at Ravenna, which after the fall of the
Ostrogoths had become the capital of Byzantine Italy. S, Vitalc was
built by the same Justinian and completed in 547 (pL IV and fig. 5).
It is an octagon with a two-storied octagonal ambulatory, a chancel
and apse added at the east end, and at the west end a narthcx or ante-*
room for the congregation to collect before entering the House of
God. The spatial motif that determines the character of the room, a
motif of purely aesthetic, Le. no functional purpose, is the use of the
niches into which the central octagon expands. As these niches arc not
enclosed by walls, but open out with arcades into the ambulatories on
the ground floor and the first floor, no clear distinction exists between
the two main parts of the building. The central space flows into the
ambulatory, and the ambulatory becomes a senseless shape if looked
at as an independent unit. The same sensation of uncertainty, of a
dreamlike; floating, is created, where solid walls remain, by the
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