The Kefeli Mosque (Turkish: Kefeli Câmîi, meaning "the mosque of the Caffariotes", after the inhabitants of the city of Caffa in Crimea, or also Kefeli Mescidi, where Mescit is the Turkish word for a small mosque) is a former Eastern Orthodox church, later jointly officiated by Roman Catholics and Armenians, and finally converted into a mosque by the Ottomans. The Catholic Church was dedicated to Saint Nicholas. Its date of dedication as Eastern Orthodox church is unknown. The interest of Kefeli Mosque arises because it reproposes the early Christian Basilica form during the later Byzantine period.
The building lies in Istanbul, in the district of Fatih, in the neighborhood of Salmatomruk, on Kasap Sokak, more or less halfway between the museum of Chora and the mosque of Fethiye.