When it comes to the “Hagia Sophia,” many people may think of the onion-topped Orthodox Church near Harbin’s Central Street, but they don’t know the Hagia Sophia, one of the “Seven Wonders of the Middle World” in Istanbul. It is the best existing example of Byzantine architecture, once the world’s largest church, and because of Turkey’s intricate historical culture, it has become a “mixed church” that has served both Jesus and Allah, both church and mosque.