This is one of a pair of guardian figures set up in the palace of Ashurnasirpal II (883-859 BC) at the Assyrian capital Kalhu. Its partner is now in the Metropolitan Museum, New York.
Stone sculptures of mythological figures, sculpted in relief or in the round, were often placed as guardians at gateways to palaces and temples in ancient Mesopotamia. These figures were known to the Assyrians as lamassu. They were designed to protect the palace from demonic forces, and may even have guarded the entrance to the private apartments of the king. The figure has five legs, so that when viewed from the front it stands firm, while when viewed from the side it appears to be striding forward to combat evil. The 'Standard Inscription' of Ashurnasirpal, common to many of his reliefs, is inscribed between the figure's legs. It records the King's titles, ancestry and achievements.
The figure was excavated by Austen Henry Layard, who worked in Assyria between 1845 and 1851. He suggested that these composite creatures combined the strength of the lion (or in this case, the bull), the swiftness of birds indicated by the wings, and the intelligence of the human head. The helmet with horns indicates the creature's divinity.