Seleucia on the Tigris

Seleucia on the Tigris, ancient city of Mesopotamia (present-day Iraq), built by King Seleucus I, sometime after 311 bc, on the west bank of the Tigris River, northeast of Babylon, which was despoiled to supply materials for its construction. Controlling the navigation of the Tigris and Euphrates rivers as well as the commerce of Mesopotamia, the city rapidly rose to wealth and splendor, becoming a famous center of Hellenistic civilization. When in the 2nd century bc Mesopotamia came under the power of Parthia, Seleucia continued as a great commercial city and in the 1st century ad had a population of 600,000. The city was partly burned by the Roman emperor Trajan in ad116, and in ad 164 it was completely destroyed by the Roman general Avidius Cassius in his campaign against the Parthians. The destruction of Seleucia marked the end of Hellenistic civilization in Mesopotamia.