Ecumenical Patriarchate of Constantinople: Currently located in the Phanar district of Istanbul, Turkey. The Ecumenical Patriarch holds a primacy of honor as 'First among equals' (Primus inter pares) among all Orthodox bishops worldwide.

The Moscow Patriarchate of the Russian Orthodox Church is a massive church possessing the most overwhelming ecclesiastical power and number of faithful among all independent Orthodox churches. With approximately 80 to 90 million members—nearly half of all Orthodox Christians—it moves the Orthodox world alongside the Ecumenical Patriarchate of Constantinople.

Serving as the state church of the modern Hellenic Republic, the Church of Greece is the autocephalous church that administratively and geographically oversees the Greek mainland. It traces its origins to the churches established by the Apostle Paul in Greek regions such as Athens, Thessaloniki, Corinth, and Crete, as recorded in the Acts of the Apostles. Under the Greek Constitution, Orthodoxy is defined as the 'prevailing religion' of the state, and approximately 80-90% of the population are members.

The Romanian Orthodox Church is an independent, self-governing Eastern Orthodox church to which the vast majority of the Romanian population belongs, and it is the largest Orthodox denomination in the Balkans. According to tradition, Saint Andrew the Apostle first brought the Gospel to the region of modern-day Romania, and he is thus revered as its patron saint.

The first patriarchate to be recognized as independent in history outside the original five (Rome, Constantinople, Alexandria, Antioch, and Jerusalem), and the oldest Slavic Orthodox church. It is a preeminent national church to which more than 60% of the total Bulgarian population belongs.

The Serbian Orthodox Church is a core denomination essential to understanding the religion and history of the Balkan Peninsula. It is the second oldest Slavic Orthodox church in the world and has served as a powerful spiritual pillar sustaining the national spirit and identity of the Serbian people.

The Patriarchate of Antioch boasts a long historical authority, second only to Jerusalem in early Christian history. It is the direct descendant of the church where the term 'Christian' was first used. According to Orthodox tradition, it was co-founded by the Apostles Peter and Paul around 34 AD, and Saint Peter served as its first bishop before going to Rome. It was one of the original five ancient patriarchates (the Pentarchy) alongside Rome, Constantinople, Alexandria, and Jerusalem.

The Greek Orthodox Patriarchate of Jerusalem is the fourth-ranked patriarchate within the global Orthodox communion and is the 'Mother Church' where Christian history began. It is the spiritual center protecting the Holy Land, the stage for the Passion and Resurrection of Jesus Christ. As the Guardian of the Holy Sepulchre, the Patriarchate is headquartered within the Church of the Holy Sepulchre, the holiest site in Christianity. The church is led by the 'Brotherhood of the Holy Sepulchre,' monks formed to manage the church and protect pilgrims.

The Patriarchate of Alexandria is an ancient patriarchate that historically holds the second rank of honor in Orthodoxy after the Ecumenical Patriarchate of Constantinople. As one of the five original centers of early Christianity (the Pentarchy), it maintains a unique status overseeing the traditions of the faith and the entire African continent.