The Church of St. George is the principal Greek Orthodox cathedral still in use in Istanbul,

Since about 1600 it has been the seat of the Ecumenical Patriarchate of Constantinople, the senior patriarchate of the Greek Orthodox Church and recognized as the spiritual leader of the world's Eastern Orthodox Christians.

The church, dedicated to the Christian martyr Saint George, is the site of numerous important services and is where the patriarch will consecrate the chrism (myron) on Holy and Great Thursday, when needed.

For this reason, the church is also known as the "Patriarchal Church of the Great Myrrh". At one time, the patriarch would consecrate all of the chrism used throughout the entire Orthodox Church.