Just after the Monastery Valley ticket office, you come to the large Büyük Kilise Cami (Mosque of the Great Church), which began life as the Church of St Gregory of Nazianzus in AD 385. St Gregory is one of the four Fathers of the Greek Church and grew up in a nearby village. Following 1924's population exchange the church became a mosque.
Check out the wooden sermon desk that was reputedly a gift from a Russian tsar.