The ruins of the building lie in Istanbul, in the district of Fatih, in the neighborhood of Salmatomruk, not far from Edirne Kapı (the ancient Gate of Charisius), more or less halfway between the Chora Church and the Fethiye Mosque.

[2] Between the ninth and the tenth century[3] a church with an underlying basement and a crypt was erected on the top of the sixth hill of Constantinople, on a plateau which is limited by the open air cistern of Aetius (now a football field) and by the unidentified Byzantine edifice denominated in Ottoman times as Boĝdan Saray.

[5] The nearby church of the Theotokos tes Kellararias, used by the nuns of the Kecharitomene as a burial place, and that of Hagios Nikolaos, both mentioned in the typikon of the nunnery, are possible candidates for the identification.

[1][8] The documented history of the edifice begins in 1475, shortly after the Fall of Constantinople, when Sultan Mehmed II conquered the Genoese colony of Caffa, in Crimea.

[1] The edifice, dedicated then to Saint Mary of Constantinople (Italian: Santa Maria di Costantinopoli), was officiated by the Dominicans, which before the Ottoman conquest had also a monastery in the city on the Black Sea.

[9] Due to all that, at the beginning of the sixteenth century the church of Saint Mary had turned into the center of this quarter predominantly inhabited by Italians, but the building fell soon in disrepair.

[11] As a consequence, and after riots between Christian and Muslims, the church was closed in 1636, and in 1640 it was transformed into a mosque by Sadrazam (Grand Vizier) Kemankeş Mustafa Pasha (d.

[19] The second church was of the cross-in-square type with an almost square naos about 10.5 m wide: it had four columns sustaining the dome through pendentives, three apses - the central one having a polygonal shape -[1] and a narthex embracing the edifice on the west and north sides.

[22] From a relation of Pietro Demarchis, bishop of Santorini, who visited Istanbul in 1622, we know that at that time the columns of the church had been taken away by the Turks and substituted with wooden pillars, and that the dome was covered with frescoes.

After the fire of 1919, the building fell into ruin (the roof collapsed and the minaret crashed already in the 1820s), but luckily it was thoroughly studied and surveyed by the German Archaeologist Paul Schatzmann in 1934/1935.

[24] In the inferior church were discovered two deesis, a fresco representing the soldier Saint Mercurius - of unparalleled technique among the known Byzantine works of this age - and prophets.