Opis (Akkadian Upî or Upija; Ancient Greek: Ὦπις) was an ancient Babylonian city near the Tigris, not far from modern Baghdad. Akkadian and Greek texts indicate that it was located on the east side of the Tigris, near the Diyala River. [1] [2] The precise site of the city has been uncertain for a long time, though at one point thought to be near or under the city of Seleucia. [3] Recent geographical surveys of ancient Mesopotamia tentatively identify Opis with the mound called Tall al-Mujailāt (or Tulūl al-Mujaili`), 20 miles (32 km) southeast in a straight line from central Baghdad and 47 miles (76 km) northeast in a straight line from ancient Babylon.

Cyrus II. defeated the Babylonian army at Opis 539 BC.

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