Ctesiphon, the imperial capital of the Persian Parthian Arsacids, and of the Persian Sassanids, was one of the great cities of ancient Mesopotamia. The ruins of the city are located on the east bank of the Tigris, across the river from the Hellenistic city of Seleucia. Today, the remains of the city lies in Baghdad Governorate, Iraq, approximately 35 km south of the city of Baghdad.