Taq Kasra arch: a 25 m centring-free brick vault
Arco de ladrillo de Taq Kasra: bóveda sin cimbra de 25 m de luz
- Date
- c. 540 · confidence low
- Place
- Ctesiphon (Salman Pak), Baghdad, Iraq
- Credited to
- Architects of the Sasanian Empire
- Field
- Tools
⚠️ Disputed: the sources disagree.
What it is
The iwan at Ctesiphon spans about 25 m and rises 37 m with an elliptical fired-brick vault built from inclined courses that lean on one another, without full centring. It was the largest brick vault span in history until modern times.
Dating is disputed: tradition credits Khosrow I (6th century), but some propose the 3rd century (Shapur I). One wing collapsed in 1888 after flooding. The inclined courses are a hypothesis of construction, not a textual record.
What it led to
- monumental iwans of Islamic architecture
- parabolic-profile brick vaults with reduced thrust
- a model of maximum-span brick vaulting in Mesopotamia