The aqueduct constructed by the Emperor Valens in AD 368 as part of a new water supply system for the city. Photo by Ergun Çagatay

c. 667 BC
Traditional date for the founding of Byzantium by Greek colonists, although archaeological evidence suggests that the site had been occupied as early as the 13th century BC.
330 AD
Emperor Constantine I dedicates a new city, built on the site of Byzantium, as the capital of the Eastern Roman Empire (the Byzantine Empire); thereafter the city is called Constantinople.