The global centre of the Greek Orthodox faith for three centuries, the Patriarchate, built in 1720, is found in an initially unattractive walled compound in the western district of the Old City called Fener, but look inside and its still one of the most interesting churches in Istanbul.rnrnIts lavish interior, especially its golden altar screen, is eye-catching though not particularly outstanding as these things go. rnrnBut if you catch a service here you’ll get a distinct sense of the culture and ceremonial tradition of the Greek Orthodox Church and so catch a glimpse of the religion that dominated Constantinople for a millennium.