Paganism flourished in Istanbul before Chistianty was established in the 14th century, when chuches began to appear. The fist churches in Istanbul were the Havariyun Church, Hagia Sophia and Hagia Eirene. Many churches were built up to the time of the Ottoman conquest and many sects were represented, i.e. Nestorians, Monophysites, Catholics, Orthodox, Assryian, Grogorian, Dominician and Francisians also the Greek, Armenian, Latin and Genoese built their own churches.

After the conquest, Sultan Mehmed the Conqueror left the churches free to worship, but in the Ottoman era many church buildings were sold and those which were derelict or abandoned were purchased and converted into mosques. The constuction of churches nevertheless continued during the Ottoman period but most were built outside the city walls in places such as Beyoglu and summer resorts as well as along the shores of the Bosphorus. After the 19th century most new churches were located close to the embassies. The prominent ones are Saint Marina Draperis, St Antoine de Padoue, Latin Italian Church, Armenian Catholic Surp Yerrontutyan Church, Terre-Seinte Spanish and British Embassy Church.