uding S. Apollinare Nuovo within and S. Apollinare in
Classe without the walls of Ravenna, the cathedral of Torcello, that is
connected by a narthex with the later S. Fosca, in which the transition
from the Roman to the Byzantine style is shadowed forth, and the
cathedrals of Parenzo and Grado in Istria, the former retaining almost
intact its beautiful colonnaded atrium, the latter chiefly remarkable
for its fine mosaic pavement.

In addition to the early churches of basilican plan are a few of
circular form, such as that at Rome enshrining the tomb of S. Constanza,
the daughter of Constantine, dating from about A.D. 354, which has a
domed roof and vaulted aisles, the 5th century church of S. Stefano
Rotondo in the same town, the latter, though greatly modified in detail,
still preserving its two concentric ranges of columns, S. Vitale at
Ravenna, and S. George at Salonika, that has a circular nave but an
oblong chancel and apse, whilst the 6th century tomb of Theodoric is
typical of the use of a similar plan in sepulchral monuments.

In the first centuries of the Christian era it was customary for the
ceremony of baptism to be performed in buildings known as baptisteries,
apart from, but close to, cathedrals and important parish churches.
These buildings were as a general rule of circular or octagonal plan
with a tank in the centre of the interior, of size sufficient for the
total immersion of candidates. The earliest and also one of the finest
existing examples is the Baptistery of Constantino that rises close to
S. Giovanni in Laterano, Rome, and is two stories high, with a central
domed roof of timber and flat-ceilinged aisles, the massive porphyry
columns dividing them from the space set apart for the ceremony of
baptism, being surmounted by slender pilasters. Another fine early
Baptistery is that at Nocera, which resembles that of Constantine in
general plan and style.

The Christians of Egyptian descent, to whom the name of Copts has been
given, evolved a style of building that combined with oriental
traditions certain details of western architecture. They were very early
familiar with the dome, and employed it in churches of a basilican
ground-plan even before it was adopted in the Roman Empire. Moreover,
certain of the barrel vaults and arches in Coptic places of worship were
pointed, so that the most distinctive characteristic of Gothic
architecture may be said to have been to some extent anticipated. Except