Eastern Orthodox Church

=== Roman/Byzantine Empire ===
{{main|State church of the Roman Empire|Ecumenical Patriarchate of Constantinople}}
[[File:Hagia_Sophia_Mars_2013.jpg|thumb|The [[Hagia Sophia]], the largest church in the world and patriarchal basilica of [[Constantinople]] for nearly a thousand years, later converted into a [[mosque]], then a museum, then back to a mosque]]

[[Constantinople]] is generally considered to be the centre and the "cradle of Orthodox [[Role of Christianity in civilisation|Christian civilisation]]".<ref>{{cite book| title = Christianity: Religions of the World | first = Ken | last = Parry | year = 2009 | isbn=9781438106397| page = 139 |publisher = Infobase Publishing |quote= }}</ref><ref>{{cite book| title = The Blackwell Companion to Eastern Christianity
| first = Ken| last = Parry| year = 2010| isbn=9781444333619| page = 368| publisher = John Wiley & Sons| quote = }}</ref> From the mid-5th century to the early 13th century, Constantinople was the largest and wealthiest city in Europe.<ref>Pounds, Norman John Greville. ''An Historical Geography of Europe, 1500–1840'', p. 124. CUP Archive, 1979. {{ISBN|0-521-22379-2}}.</ref> Eastern [[Christian culture]] reached its golden age during the high point of the [[Byzantine Empire]] and continued to flourish in Ukraine and Russia, after the [[fall of Constantinople]]. Numerous [[Autocephaly|autocephalous]] churches were established in Europe: Greece, Georgia, Ukraine, as well as in Russia and Asia.

In the 530s the [[Hagia Sophia|Church of the Holy Wisdom]] (Hagia Sophia) was built in [[Constantinople]] under Emperor [[Justinian I]].<ref>{{cite web|url=http://archnet.org/sites/1989 |title=Hagia Sophia |publisher=Archnet |access-date=12 March 2016}}</ref> Beginning with subsequent [[Byzantine architecture]], Hagia Sophia became the paradigmatic [[Eastern Orthodox church architecture|Orthodox church form]] and its architectural style was emulated by [[Ottoman architecture#Classical period (1437–1703)|Ottoman mosques]] a thousand years later.<ref name=Heinle1996>{{harvnb|Heinle|Schlaich|1996}}</ref> Being the [[episcopal see]] of the [[Ecumenical Patriarch of Constantinople|ecumenical patriarch of Constantinople]], it remained the world's largest cathedral for nearly a thousand years, until [[Seville Cathedral]] was completed in 1520. [[Hagia Sophia]] has been described as "holding a unique position in the [[Christian world]]",<ref name=Heinle1996/> and architectural and [[cultural icon]] of [[Byzantine culture|Byzantine]] and [[Eastern Orthodox Culture|Eastern Orthodox civilisation]],<ref>{{harvnb|Cameron|2009}}.</ref><ref name=M19>{{harvnb|Meyendorff|1982}}.</ref> and it is considered the epitome of [[Byzantine architecture]]<ref name=BAT>{{cite book|last1=Fazio|first1=Michael|title=Buildings Across Time|last2=Moffett|first2=Marian|last3=Wodehouse|first3=Lawrence|publisher=McGraw-Hill Higher Education|year=2009|isbn=978-0-07-305304-2|edition=3rd}}</ref> and is said to have "changed the history of architecture".<ref name=nytimes22>{{cite news|last=Simons|first=Marlise|date=22 August 1993|title=Center of Ottoman Power|work=The New York Times|url=https://www.nytimes.com/1993/08/22/travel/center-of-ottoman-power.html|access-date=4 June 2009}}</ref>