Which city was the principal capital of the Sasanian Empire?

Ctesiphon was the principal capital of the Sasanian Empire. The city stood on the Tigris River in Mesopotamia, near modern Baghdad, and developed from an earlier royal settlement associated with the Parthian Empire.

Under the Sasanians, Ctesiphon became the main seat of the shahanshah, or King of Kings. It was a major political, commercial, and cultural center, positioned close to the empire’s western frontier and to the important routes linking Mesopotamia, Iran, and the Roman world. The famous Taq Kasra, or Arch of Ctesiphon, is a surviving monument associated with the city’s grand architecture.

Ctesiphon was not the same place as Persepolis, the Achaemenid ceremonial center farther east in Iran. Sasanian rulers also used other royal residences, but Ctesiphon remained the empire’s principal metropolitan capital until the dynasty’s collapse in the seventh century.