The typical late Byzantine church is a development from the domed cross plan. In three examples in Constantinople, S. Theodosia (pp. 170, 172), S. Mary Diaconissa (p. 185), and SS. Peter and Mark (p. 193), we can trace the gradual disappearance of the galleries. S. Theodosia, as has already been mentioned, has galleries in all three cross arms. In S. Mary Diaconissa they are confined to the four angles between the cross arms; SS. Peter and Mark is a simple cross plan without galleries. In later times it became customary to build many small churches, with the result that the chambers at the angles of the cross, of little account even in a large church, were now too diminutive to be of any value, and the question how to provide as much room as possible for the worshippers became paramount. Accordingly the dome piers were reduced to mere columns connected with the outer walls of the building by arches; and thus was produced the typical late Byzantine plan--at the ground level a square, enclosing four columns; above, a Greek cross with a dome on the centre.
[Illustration: FIG. 6.--THE CHURCH OF THE KOIMESIS, NICAEA (Rott).]
From its distinguishing feature this type has been styled the 'four column' plan. It appears in many Constantinopolitan churches, as, for example, S. Theodore (p. 248) and S. Saviour Pantepoptes (p. 214). The cross arms are not always equal, and may be covered with barrel vaults (p. 214) or with cross-groined vaults (p. 198). The bema is usually a bay added to the eastern arm. The angle chambers have either cross-groined vaults or flat dome vaults. In general the churches of this type in Constantinople do not differ from the numerous churches of the same class in the provinces.[19]
A lobed cruciform plan is found in only one church in Constantinople, that of S. Mary of the Mongols (p. 277). Here the central dome is supported on four piers set across the angles of the square, so that the pendentives do not come to a point as usual, but spring from the face of the piers. Against each side of the square a semi-dome is set, thus producing a quatrefoil plan at the vaulting level.
Both trefoiled and quatrefoiled churches are not uncommon in Armenia, such as the cathedral at Etschmiadzin;[20] trefoiled churches of a later date are found in the western provinces, and examples have been published from Servia,[21] Salonica,[22] and Greece.[23]