The lamassu is a celestial being from Mesopotamian mythology. Human above the waist and a bull below the waist, it also has the horns and the ears of a bull. It appears frequently in Mesopotamian art, sometimes with wings. The lamassu and shedu were household protective spirits of the common Babylonian people. Later during the Babylonian period they became the protectors of kings as well always placed at the entrance. Statues of the bull-man were often used as gatekeepers. The Akkadians associated the god Papsukkal with lamassu and the god Išum with shedu.
From the ninth to the seventh century B.C., the kings of Assyria ruled over a vast empire centered in northern Iraq. The first great Assyrian king was Ashurnasirpal II (r. 883–859 B.C.), who undertook a vast building program at Nimrud, ancient Kalhu. Until it became the capital city under Ashurnasirpal, Nimrud had been no more than a provincial town.
The new capital occupied an area of about 900 acres, around which Ashurnasirpal constructed a mud-brick wall 120 feet thick, 42 feet high, and 5 miles long. In the southwest corner of this enclosure was the acropolis, where the temples, palaces, and administrative offices of the empire were located. In 879 B.C. Ashurnasirpal held a festival for 69,574 people to celebrate the construction of the new capital, and the event was documented by an inscription that read: "the happy people of all the lands together with the people of Kalhu—for ten days I feasted, wined, bathed, and honored them and sent them back to their home in peace and joy."