As already intimated, to this church belongs the interest of having always preserved its original character as a sanctuary of the Greek Orthodox Communion. This distinction it owes to the fact that the church was given to Christoboulos, the Greek architect of the mosque of Sultan Mehemed, as his private property, to mark the conqueror's satisfaction with the builder's work. The grant was confirmed by Bajazet II. in recognition of the services of the nephew of Christoboulos in the construction of the mosque which bears that Sultan's name. Twice, indeed, attempts were subsequently made to deprive the Greek community of the church, once under Selim I. and again under Achmed III. But, like the law of the Medes and Persians, a Sultan's decree altereth not, and by presenting the hatti sheriff of Sultan Mehemed the efforts to expropriate the building were frustrated.[481] Among the Turks the building is known as Kan Kilisse, the church of Blood, and the adjoining street goes by the name Sanjakdar Youkousou, the ascent of the standard-bearer,[482] terms which refer to the desperate struggle between Greeks and Turks at this point on the morning of the capture of the city.[483] _Architectural Features_ Although the building has always been in Christian hands it has suffered alterations almost more drastic than any undergone by churches converted into mosques. The interior has been stripped of its original decoration, and is so blocked by eikons, chandeliers, and other ornaments as to render a proper examination of the church extremely difficult. In plan the church is a domed quatrefoil building, the only example of that type found in Constantinople. The central dome rests on a cross formed by four semi-domes, which are further enlarged below the vaulting level by three large semicircular niches. It is placed on a drum of eight concave compartments pierced by windows to the outside circular and crowned with a flat cornice. Externally the semi-domes and apse are five-sided. From the interior face of the apse and on its northern wall projects a capital, adorned with acanthus leaves, which, as it could never have stood free in this position, probably formed part of an eikonostasis in stone. The narthex is in three bays, the central bay being covered by a barrel vault, while the lateral bays have low drumless domes on pendentives. The entrance is by a door in the central bay, and from that bay the church is entered through a passage cut in the central niche of the western semi-dome, and slightly wider than the niche. The end bays open, respectively, into the northern and southern semi-domes by passages or aisles terminating in a diagonal arch. The arches between these aisles and the western semi-dome are pierced, and thus isolate the western dome piers. On the south the church has been greatly altered; for the entire southern semi-dome and the southern bay of the narthex have been removed and replaced by three aisles of two bays each. These