Ctesiphon was the capital city of the Parthian and Sasanian Empires (247 BC–224 AD and 224–651 respectively). It was one of the great cities of late ancient Mesopotamia.Its most conspicuous structure remaining today is the great archway of Ctesiphon.It was situated on the eastern bank of the Tigris across from where the Greek city of Seleucia stood and northeast of ancient Babylon.