Ctesiphon, Ancient city in Iraq
Ctesiphon was an ancient city located on the eastern bank of Tigris, and about 35 kilometre southeast of present day Baghdad.
It served as a royal capital of Persian Empire in the Parthian and Sasanian era for over eight hundred years.
Ctesiphon is culturally significant as it was one of the greatest cities in the world from the Roman period onwards until its downfall.
The Taq Kasra, also known as the Archway of Ctesiphon, is the only visible remaining structure of the city.
The archway is the largest single-span vault of unreinforced brickwork in the world.
Location: Asuristan
Inception: 120s BCE
Population: 500000
Source: Wikimedia