Tāq Kasrā, Ctesiphon imperial palace complex

Ctesiphon is one of the great cities of ancient Mesopotamia and the capital of the Parthian Empire and its successor, the Sassanid Empire, for more than 800 years. It is believed that Ctesiphon was the largest city in the world from 570 to 637. The remains of imperial palace are all that survives of the great city above ground.

The ruins of Ctesiphon were the site of a major battle of World War I in November of 1915. The Ottoman Empire defeated troops of Britain attempting to capture Baghdad, and drove them back some 40 miles before trapping the British force and compelling it to surrender.