The Ecumenical Patriarchate of Constantinople is the symbolic headquarters of the Greek Orthodox Church, and one of the most significant sites in the larger Eastern Orthodox Church. It has been led by 270 Ecumenical Patriarchs since its establishment in 330 AD. This compound of buildings nestled behind the sea walls fronting the Golden Horn includes the beautiful 19th-century Patriarchal Church of St George.
To the Turkish government, the Ecumenical Patriarch is a Turkish citizen of Greek descent nominated by the Church and appointed by the government as an official in the Directorate of Religious Affairs. In this capacity the patriarch is the religious leader of the country's Orthodox citizens and is known officially as the Greek Patriarch of Fener (Fener Rum Patriği).
The Patriarchate has been based in a series of churches over its history, including Hagia Eirene (Aya İrini; 272–398), Hagia Sofya (Aya Sofya; 398–1453) and the Church of Pammakaristos (Fethiye Museum; 1456–1587). It moved to its current location in Fener in 1601.
The relationship between the Patriarchate and the wider Turkish community has been strained in the past, no more so than when Patriarch Gregory V was hanged for treason after inciting Greeks to overthrow Ottoman rule at the start of the Greek War of Independence (1821–32).
Current tensions are focused on the Turkish government's refusal to allow the the Patriarchate to reopen the Orthodox Theological School of Halki, located on Heybeliada in the Princes' Islands. Opened in 1844, the school was closed by government order in 1971. The US Commission on International Religious Freedom (USCIRF) is one of the organisations calling on Turkey to reopen the seminary.