four bays covered with cross-groined vaults on
transverse arches. Its southern bay, however, is a later extension,
running about half-way in front of the central church to give access to
a door into that building. Only two bays of the original narthex have
doors opening into the north church; the third door which once existed
in the northern bay has been partly built up. The narthex is very much
out of repair, and the western wall threatens to fall outwards. The
dome, pierced by eight windows, shows so many Turkish features that it
may be pronounced as mostly, if not wholly, a Turkish construction. The
four square piers which support it are manifestly Turkish. When Gyllius
visited the church in the sixteenth century the dome arches rested on
four columns of Theban granite, 'hemispherium sustentatur quatuor
arcubus, quos fulciunt quatuor columnae marmoris Thebaici.'[403] Barrel
vaults cover the arms of the cross, which, as usual in churches of this
type, appears distinctly above the roof on the exterior. The southern
arm extends to the central church and its vault is pierced by two
windows, inserted, probably, to compensate for the loss of light
occasioned by the erection of that building. These windows furnish one
indication of the earlier date of the north church. The gynaeceum, like
the narthex below it, is covered with cross-groined vaults and contains
a small fireplace. The prothesis and diaconicon have barrel vaults and
apses with three sides projecting slightly on the exterior. The main
apse has a very lofty triple window, and shows five sides. All the apses
are decorated with high shallow blind niches, a simple but effective
ornament.[404]

_The Central Church._--The central church is an oblong hall covered by
two domes, and terminates in a large apse. It is extremely irregular in
plan, and does not lie parallel to either of the churches between which
it stands. The domes are separated by a transverse arch. The western
dome, though flattened somewhat on the four sides, is approximately
circular, and divided into sixteen shallow concave compartments, each
pierced by a window. Some of these windows must have been always blocked
by the roof of the north church. The eastern dome is a pronounced oval,
notwithstanding the attempt to form a square base for it by building a
subsidiary arch both on the south and on the north. It is divided into
twenty-four concave compartments, twelve of which have windows. The
drums of