A city and important cultural center at the heart of Sumer of southern Mesopotamia (now Iraq), first occupied in 'Ubaid times and inhabited into the 1st millennium AD. Nippur played a special role in the life of Sumer as a religious city, center of the worship of Enlil. Lying between the Tigris and Euphrates rivers, its remains include the Temple of Enlil and its ziggurat, sequence of Early Dynastic temples, Old Babylonian residences, and Uruk pottery of the 4th millennium BC. Its fame rests primarily on the discovery of cuneiform tablets of the sacerdotal library, which have yielded more of the literary tradition of the Sumerians than any other Mesopotamian site. The tablets range in date from the late 3rd millennium to the later 1st millennium BC and include both administrative, cultic, economic, and literary texts. There is an extremely detailed sequence of pottery covering most of the pre-Islamic period of southern Iraq, much from the Inanna temple precinct.