Ctesiphon

Ctesiphon, city of ancient Mesopotamia, on the eastern bank of the Tigris River, opposite Seleucia. Ctesiphon was the winter residence of the Parthian kings and later the capital of the Parthian kingdom. When the Arsacid dynasty of Parthian rulers was overthrown, about ad 224, the city became the capital of the Sassanid dynasty of Persian kings. Plundered by the Arabs in 637, the city was abandoned when the Abbasid caliphs made their capital at nearby Baghdād. The ruins of Ctesiphon, in modern Iraq, are noted for the remains of a great vaulted hall of the Sassanian period.