ilding are derived the various schemes on
which the churches of the Byzantine Empire were planned.

Of the basilican form the only example in Constantinople that retains
its original plan is S. John the Baptist of the Studion (p. 56), erected
_c._ 463 A.D.

The church of SS. Sergius and Bacchus (p. 70) and the baptistery of S.
Sophia (p. 78) represent respectively the two varieties of the octagonal
plan. In the former the dome rests on piers surrounded by an ambulatory;
in the latter the dome rests upon the outer walls of the buildings. Both
are foundations of Justinian the Great.

Of the Cross church plan showing the cross externally at the ground
level no example survives in the city. But at least one church of that
form was seen at Constantinople in the case of the church of the Holy
Apostles. This was essentially a mausoleum, built originally by
Constantine the Great and reconstructed by Justinian to contain the
sarcophagi of the sovereigns and the patriarchs of New Rome.[12]

The church of S. Mark at Venice was built on the plan of the Holy
Apostles. It is a cruciform church with aisles, but the galleries which
might have been expected above them are omitted. The central dome rests
on four piers, and four smaller domes cover the arms.

Professor Strzygowski gives examples of cross-planned cells in the
catacombs of Palmyra,[13] and in many Eastern rock tombs.[14] Such cross
plans are found also in the Roman catacombs. These subterranean chapels,
of course, do not show the external treatment, yet there can be little
doubt that the external cross plan was originally sepulchral, and owes
its peculiar system of planning to that fact. On the other hand, it was
adopted in such churches as S. Mark's at Venice and in the French
examples of Perigord for aesthetic or traditional reasons.

In passing now to a consideration of the distinct forms developed from
these pre-Byzantine types of church building, the classification adopted
by Professor Strzygowski may be followed. In his _Kleinasien_ he has
brought forward a series of buildings which show the manner in which a
dome was fitted to the oblong basilica, producing the domed basilica
(_Kuppelbasilica_), an evolution which he regards as Hellenistic and
Eastern. In contrast to this, Strzygowski distinguishes the domed cross
church (_Kreuzkuppelkirche_), of which S. Theodosia in Constantinople
(p. 170) is the typical example and which is a Western development. A
compariso