Ayasofia and The church of St.George in Istanbul were very interesting places for me, who studied Russian language. According to the Primary Chronicle, in the 10th century, Vladimir, the prince of Kievan Rus’, decided to adopt Orthodox Christianity as the state religion. Before making his decision, he sent delegations to various regions, including Volga Bulgaria, the Khazar Khanate, Constantinople, and Rome (or the Holy Roman Empire). The delegates reported back to Vladimir, expressing how deeply impressed they were by the Orthodox faith. As a result, he chose to adopt it for his realm. At that time, Hagia Sophia served as the seat of the Patriarchate of Constantinople. Today, that role is held by the Church of St. George.