The Ecumenical Orthodox Patriarchate is an autocephalic (self-governed and appointed archbishop) church in Fatih, Istanbul, which is the head of most eastern Orthodox churches (primus inter pares), currently ruled by Bartholomeos I.

It was founded by Andrew, one of the 12 apostles of Jesus, and became independent in 330. It is of particular importance as it is located in the capital of the Eastern Roman Empire and is the head of many Orthodox churches. Unlike the Pope, the Archbishop does not interfere with other autocephalic churches and is regarded as the religious leader of approximately 300 million Orthodox Christians in the world.

After the conquest of Istanbul in 1453 by Ottoman Turks, The Ecumenical Patriarchate gained a status according to the decree issued by Mehmet II. and remained in a situation where the Ottoman Empire did not interfere with its internal affairs.

St. George's Cathedral (also known as The Church of St. George), where the Patriarchate continues its activities today, was built in 1602. From The Church of the Holy Apostles (550-1455) in Fatih district, Pammakaristos Church (also known as The Church of Theotokos Pammakaristos) in Fatih district (today Fethiye Mosque) (1455-1586), Church of St. Mary of Blachernae in Fener district (1586-1597) and Ayios Dimitrios Church in Ayvansaray district (1597-1602).

The Patriarchate building (St. George's Cathedral) is often confused with The Phanar Greek Orthodox College (or Phanar Roman Orthodox Lyceum) building. St. George's Cathedral and The Orthodox College are two different buildings, although they are located close to each other. The restoration works of St. George's Cathedral, initiated by the Istanbul 1st Regional Directorate General of Foundations in 2014, ended in 2017 and was restored to its original form by the help of the restoration works.

ticm Calce was used in the restoration works of St. George's Cathedral and Phanar Greek Orthodox College, which is often confused. Calce is a natural hydraulic lime with CE certificate and is widely used in Turkey and abroad to be used in the restoration projects of historical buildings. Calce is also preferred in green building applications, in the production of brickdust mortar, in the creation of plaster and joint mortar, in masonry wall works.

Calce has a porous structure allowing vapor permeability, that is, breathable, which prevents the formation of dampness and decay. It has low sulphate and alkali content, and it is a sustainable material compared to cement, it does not contain salts which reacts with mortars used in historical buildings and damages them like cement does, and it allows small deformations. These can be listed as reasons why natural hydraulic lime is preferred instead of cement as a binder in historical buildings.