The 6th-century Persian monument Taq Kasra, or Arch of Ctesiphon, is the world’s largest brick vault. The site is the most famous architectural site of Persian Empire during Sassanian dynasty. Taq Kasra was mainly destroyed in 7th-century AD during the Muslim Arabs conquest of Persia (Iran), but it remained as a source of inspiration for Persian and Arab poets in the Medieval era.
The arch ruin is now located outside Persia, close to Iraqi capital Baghdad and is in danger in view of more than a quarter of century violation in the region.
At the moment the arch is under the protection of Iraqi police. Iraq has already started efforts to register Taq Kasra as a UNESCO World Heritage Site.