Taq Kasra is the surviving vaulted hall of the Sasanian imperial palace at Ctesiphon, southeast of Baghdad. Its great brick iwan is still astonishing in scale: a single soaring arch from one of the pre-Islamic world's most important capitals.
The site has suffered neglect, instability, and structural damage, so conditions can change and visits need current local advice. For historically minded travelers in Baghdad, though, it is one of the region's essential ancient monuments.