This map shows two of the most prominent regions during Constantine’s rule. Constantinople (modern-day Istanbul) was the namesake capital city of the Roman Empire founded in 330 and dissolved in 1453. 87 miles (140 km) to the south is Nicea (modern-day Iznik). The council of bishops that took place in 325 established a consensus on the Holy Trinity.
“The Great Schism” in the 11th century split Europe down through the Mediterranean – it was essentially a “formal break between Rome and Constantinople.” (McCulloch, 362) The two opposing cities differed on interpretations of faith, practices, doctrines, icons, God’s will, and the nature of man.
(Azkoul, Michael (1994). “What are the differences between Orthodoxy and Roman Catholicism.” The Orthodox Christian Witness. 27 (48))