Monastery of Kyra Martha

Manastır Mosque (Turkish: Manastır Mescidi; also Mustafa Çavuş Mescidi, where mescit is the Turkish word for a small mosque) is a former Eastern Orthodox church converted into a mosque by the Ottomans. Neither archeological excavations nor medieval sources have made it possible to find a satisfactory answer as to its original dedication as a church. It is however possible that the small building was part of the Byzantine monastery dedicated to the Holy Martyrs Menodora, Metrodora, and Nymphodora (Greek: Μονῆ τῶν Άγίων Μηνοδώρας, Μητροδώρας καὶ Νυμφοδώρας), or an annex of the nunnery of Kyra Martha (Greek: Μονῆ τἠς Κὑρας Μάρθας). The edifice is a minor example of Byzantine architecture in Constantinople, and is important for historical reasons.

The medieval structure lies in Istanbul, in the district of Fatih, in the neighborhood of Topkapı, on the south side of Turgut Özal Caddesi, about six hundred metres (2,000 feet) south east of the Topkapı Gate of the city walls. The building can be easily reached from the center by the T1 Tram.

The origin of this building, which lies on the seventh hill of Constantinople, is unclear. As its Turkish name suggests, it is possible that it was a small chapel belonging to a monastery, possibly that dedicated to the Holy Martyrs Menodora, Metrodora, and Nymphodora, which existed near the Gate of St. Romanus (today Topkapı, in Turkish “Gate of the gun”), in the neighborhood of Constantinople named ta Elebichou. In the first half of the 14th century, a certain Phokas Maroulas, domestikos of the imperial table, restored the church and dedicated it to the Theotokos, founding a small monastery.

...
Wikipedia