The historically important site of Ctesiphon, about 30 km to the south east of Baghdad, was built by the Parthian Persians on the opposite (east) side of the Tigris from Seleucia in the middle of the 2nd century BC. The two cities were joined by a bridge, and the Arabs coupled them together, calling them jointly Al-Mada'en (the Cities).
Amidst its extensive ruin stands the best-known antique site in Iraq after Ur and Babylon: the fabulous and colossal arch of the great banqueting-hall of the great palace of Sapor, the Shah's luxurious capital, which was built in the middle of the 3rd century of our era.
Experts believe that it is the widest and highest single-span vault built of baked bricks in the World: its construction at that time must have been a miracle of architectural planning.
A descendant of ancient Mesopotamian structures in style, it embodied a skilful development of temples and palaces of the 3rd millennium BC, when the front part of great buildings would consist of large halls topped by high arches - as seen clearly at the entrances of Assyrian cities.
When the Tigris flooded in 1987 and destroyed almost all of the rest of the building, the Arch of Ctesiphon survived.