Orthodox Christians are holding a Divine Liturgy mass at an ancient monastery on the Turkish Black Sea coast after the government allowed worship there once a year.
Christians from across Europe are travelling to Sumela
For the first time in more than 80 years, Orthodox Christians are meeting at a 1,600-year-old monastery on Turkey's Black Sea coast. Between 10,000 and 20,000 Christians from Greece, Georgia and Russia are expected to travel to the Sumela monastery, south of Trabzon.
The monastery is of particular historical importance to Greek Orthodox Christians.
Before the state of Turkey was founded, there were 300,000 Greeks living in this area of the Black Sea coast. But after the 1922 Treaty of Lausanne between Greece and Turkey, the Greeks had to leave the country. The Sumela monestary then was abandoned.
Turkish authorities have reopened the Byzantine-era monastery - built nearly 300 meters (1000 feet) into the side of a mountain - for once yearly worship.
In recent years the Sumela monastery has just been a tourist attraction
"A historic moment"
The last Divine Liturgy at the Sumela cloisters was read in 1926, and so for many Greeks it is a special moment to be make a pilgrimage to a place of worship of their ancestors.
One pilgrim told German state broadcaster ARD that it was "a historic moment."
"Finally, and after several decades and the catastrophe of 1922, once again the sound of Holy Mass in the historic monastery of Sumela will be heard," he said.
Another pilgrim called it "a historic moment for both nations, for the Greeks and the Turks."
Sunday's service at the Byzantine-era monastery is being led by Patriarch Bartholomew I, the spiritual leader of the world's Orthodox Christians
The service is seen as a move by the Islamic-oriented Turkish government to loosen restrictions on religious expression and try and improve relations with non-Muslim minorities.
However nationalist factions within Turkey have accused the government of betrayal.
Author: Catherine Bolsover (ARD/AP)
Editor: Sonia Phalnikar