The Ecumenical radiation of the Patriarchal Throne of Constantinople had as its nucleus the authentic way of life of the apostolic tradition. Andrew the Apostle and John the Evangelist spread the Christian religion throughout the East and were the roots of the Ecumenical Throne. The first Bishop of Byzantium, as was then called the City, was Apostolos Andreas or Andrew the Apostle.
The founding of the New Rome, Constantinople, by Constantine the Great in 330 AD was the starting point for the creation of a new civilization which would combine Greek tradition with the new values brought into the world by the Christian religion. So the Palace, the Hippodrome, the roads and squares, were combined with the parallel positioning of the churches of St. Sophia, St. Irene and the Holy Apostles.
Saint Sophia was identified with the Ecumenical Patriarchate for more than a thousand years. It was also identified with one of the greatest periods of human conception and creation. The enormous responsibility borne by the Throne of Constantinople for the Ecumenical Church became increasingly great after the fall of the Western State under the attacks of the barbarian tribes (476 AD) and the expansion of Arab domination at the Patriarchates of the East during the 7th century. Thus, it was the duty of the byzantine emperors to strengthen the wider ecumenical mission of the Patriarchate of Constantinople.
The Patriarchate organized missions throughout the area stretching from Central Europe to the Volga. a perfect model of missionary activity was that of the brothers Cyril and Methodios from Thesaloniki, who devised the Slavonic alphabet, which constituted the basis of the Russian, Bulgarian and Serbian alphabets, in order for the preaching of the faith and the experience of divine worship to be offered in the mother tongue of the Slavic peoples (9th c.). With this work the new identity of the peoples of Eastern Europe was established and developed.
After the fall of Constantinople (29 May 1453), the Ecumenical Patriarch shouldered the responsibilities of Ethnarch for all the Orthodox peoples of the Ottoman State and undertook administrative and juridicial responsibilities in civil cases concerning the Orthodox. In 1599 the Ecumenical Patriarchate settled in Phanar, the historic area of Constantinople, where it remains until today. One of the most important activities was to awaken the Nation of Greeks (or Romeoi) from the darkness of slavery and to enlighten, making them aware of the glorious past of their country.
The first efforts for the establishment of a Greek School in Constantinople, during ottoman occupation began in the 16th century. The Patriarchal School of Ioassaf II (1556-1565) with the help of Ioannes Zygomalas will be the forerunner of the Great School of the Nation (I Megali tou Genous Sxoli).
In 1625 the Patriarchal School opened again, under the direction of Theofilos Korydaleas, with many students. But the liberal ideas of Korydaleas were annoying and the school closed. In 1662 the school acquired permanent income, a building and remarkable teachers, among them Alexandros Mavrokordatos who bore the title Confidant.
In the middleof the 19th century the Great School began to offer great and wide services to the Nation. The School graduates taught in the Greek Schools of all the regions. In 1882 during the Patriarchate of Joachim III, the Great School of the Nation was housed in a new, large building in the area of Phanar. Today it houses a middle and high school of the Greek minority.