The North Church.—The north church is of the normal 'four column' type. The four columns which originally supported the dome were, however, removed when the building was converted into a mosque in Turkish times, and have been replaced by two large pointed arches which span the entire length of the church. But the old wall arches of the dome-columns are still visible as arched piercings in the spandrils of the Turkish arches. A similar Turkish 'improvement' in the substitution of an arch for the original pair of columns is found in the north side of the parecclesion attached to the Pammakaristos (p. [152]). The dome with its eight windows is likewise Turkish. The windows are lintelled and the cornice is of the typical Turkish form. The bema is almost square and is covered by a barrel vault formed by a prolongation of the eastern dome arch; the apse is lighted by a lofty triple window. By what is an exceptional arrangement, the lateral chapels are as lofty both on the interior and on the exterior as is the central apse, but they are entered by low doors. In the normal arrangement, as, for instance, in the Myrelaion, the lateral chapels are low and are entered by vaults rising to the same height as those of the angle chambers, between which the central apse rises higher both externally and internally.
The chapels have niches arched above the cornice on three sides, and are covered by cross-groined vaults which combine with the semicircular heads of the niches to produce a very beautiful effect. To the east they have long bema arches flanked by two small semicircular niches, and are lighted by small single windows.
The church is preceded by a narthex in three bays covered by cross-groined vaults supported on strong transverse arches. At either end it terminates in a large semicircular niche. The northern one is intact, but of the southern niche only the arched head remains. The lower part of the niche has been cut away to afford access to the narthex of the south church. This would suggest that, at least, the narthex of the south church is of later date than the north church.
Considered as a whole the north church is a good example of its type, lofty and delicate in its proportions.
The South Church.—The narthex is unsymmetrical to the church and in its present form must be the result of extensive alteration. It is in two very dissimilar bays. That to the north is covered with a cross-groined vault of lath and plaster, probably on the model of an original vault constructed of brick. A door in the eastern wall leads to the north aisle of the church. The southern bay is separated from its companion by a broad arch. It is an oblong chamber reduced to a figure approaching a square by throwing broad arches across its ends and setting back the wall arches from the cornice. This arrangement allows the bay to be covered by a low drumless dome. Two openings, separated by a pier, lead respectively to the nave and the southern aisle of the church.
The interior of the church has undergone serious alterations since it has become a mosque, but enough of the original building has survived to show that the plan was that of an 'ambulatory church.'
Each side of the ambulatory is divided into three bays, covered with cross-groined vaults whose springings to the central area correspond exactly to the columns of such an arcade as that which occupies the west dome bay of S. Andrew (p. [114]). We may therefore safely assume that triple arcades originally separated the ambulatory from the central area and filled in the lower part of the dome arches. The tympana of these arches above were pierced to north, south, and west by three windows now built up but whose outlines are still visible beneath the whitewash which has been daubed over them. The angles of the ambulatory are covered by cross vaults.
The pointed arches at present opening from the ambulatory to the central area were formed to make the church more suitable for Moslem worship, as were those of the north church. In fact we have here a repetition of the treatment of the Pammakaristos ([p. 151]), when converted into a mosque. The use of cross-groined vaults in the ambulatory is a feature which distinguishes this church from the other ambulatory churches of Constantinople and connects it more closely with the domed-cross church. The vaults in the northern portion of the ambulatory have been partially defaced in the course of Turkish repairs.
