Paganism flourished in İstanbul before Christianity was established in the 4th century, when churches began to appear. The first churches in İstanbul were the Havariyun Church, Haghia Sophia and Haghia Irini. Many churches were built up to the time of the Ottoman Conquest and many sects were represented. i.e. Nestorians, Monophysites, Catholics, Orthodox, Assyrian, Gregorian, Dominican and Francisians. Also the Greek , Armenian, Latin and Genoese built their own churches.