ee principal types
of church plan prevailed in the Roman world:--

I. The Basilica: an oblong hall divided into nave and aisles, and roofed
in wood, as in the Italian and Salonican examples, or with stone
barrel-vaults, as in Asia Minor and Central Syria.

II. The Octagonal or Circular plan covered with a stone or brick dome, a
type which may be subdivided according as (1) the dome rests upon the
outer walls of the building, or (2) on columns or piers surrounded by an
ambulatory.

The Pantheon and the so-called Temple of Minerva Medica at Rome are
early examples of the first variety, the first circular, the second a
decagon in plan. S. George at Salonica is a later circular example. An
early instance of the second variety is found in S. Constanza at Rome,
and a considerable number of similar churches occur in Asia Minor,
dating from the time of Constantine the Great or a little later.

III. The Cross plan. Here we have a square central area covered by a
dome, from which extend four vaulted arms constituting a cross. This
type also assumes two distinct forms:

(1) Buildings in which the ground plan is cruciform, so that the cross
shows externally at the ground level. Churches of this class are usually
small, and were probably sepulchral chapels rather than churches for
public worship. A good example is the tomb of Galla Placidia at Ravenna.

(2) In the second form of the Cross church the cross is enclosed within
a square, and appears only above the roofs of the angle chambers. An
example is seen in the late Roman tomb at Kusr en Nueijis in Eastern
Palestine. In this instance the central square area is covered with a
dome on continuous pendentives; the four arms have barrel-vaults, and
the angles of the cross are occupied by small chambers, which bring the
ground-plan to the square. The building is assigned to the second
century, and shows that true though continuous pendentives were known at
an early date[10] (Fig. 8).

Another example is the Praetorium at Musmiyeh, in Syria,[11] which
probably dates from between 160 and 169 A.D. At some later time it was
altered to a church, and by a curious foreshadowing of the late
Byzantine plan the walls of the internal cross have entirely disappeared
from the ground-plan. The dome rests on four columns placed at the inner
angles of the cross, and the vaulted cross arms rest on lintels spanning
the space between the columns and the outer walls.

From these three types of bu