The city of Byzantium was dedicated to the Greek goddess Artemis in 667 BC, whose symbol, the crescent moon, was used as the symbol of the city for nearly 1000 years between 667 BC and 330 AD.
When the city of Byzantium became Christian in 330 AD, a star was added to the Crescent of Artemis emblem as it assumed the significance of an attribute of the Virgin Mary.
c. 1400
Roman (Byzantine) Empire
The only attested flag of the Byzantine Empire under the Palaeologi, early 15th century. It depicts St George's Cross and the Arms of the Palaiologos family.
Likely flag of the Ecumenical Patriarchate of Constantinople after the restoration of the Empire in 1261. This derivative depicts the double-headed eagle holding a cross and orb.