What is the name of the great Sasanian vaulted hall at Ctesiphon?

The great Sasanian vaulted hall at Ctesiphon is called Taq Kasra.

Also known as the Arch of Ctesiphon, Taq Kasra is the surviving brick iwan of a monumental palace complex near the ancient Sasanian capital. Its enormous barrel vault is one of the best-known surviving examples of Sasanian architecture.

The structure is traditionally associated with the reign of Khosrow I, who ruled from 531 to 579 CE, although its exact construction date and original function remain debated. It probably formed part of a royal audience or palace complex rather than standing as an isolated monument.

Taq Kasra is often confused with the Apadana, the columned audience hall at Persepolis. The Apadana belonged to the much earlier Achaemenid Empire, while Taq Kasra belongs to the later Sasanian period.