Seleucia (/sɪˈluːʃə/), also known as Seleucia-on-Tigris or Seleucia on the Tigris, was a major Mesopotamian city of the Seleucid, Parthian, and Sassanid empires. It stood on the west bank of the Tigris River opposite Ctesiphon, within the present-day Babil Governorate in Iraq.