Arch of Ctesiphon

Situated 30km south of Baghdad, east of the Tigris, the now ruined city of Ctesiphon was first built in the second century BC by the Parthian Persians.

Today there is very little left of its former glories, except a colossal arch which is thought to have once formed part of a great banqueting hall. Experts believe that it is the widest, single-span vault in the world. When the Tigris flooded in 1987 and destroyed almost all of the rest of the building, the Arch of Ctesiphon survived.