Nippur (nĬpŏŏr´), ancient city of Babylonia, a N Sumerian settlement on the Euphrates. It was the seat of the important cult of the god Enlil, or Bel. Excavations at Nippur have yielded the remains of several temples that date from the middle of the 3d millennium BC and were later rebuilt and restored many times. Over 40,000 clay tablets found there serve as a primary source of information on Sumerian civilization. Assurbanipal erected a ziggurat in Nippur. Relics of the Persian and Parthian periods have also been unearthed at the site.