A lamassu is a human-headed, winged bull or lion. These colossal limestone sculptures guarded Assyrian palace doorways and city gates. The monumental sculptures served to ward off the king's enemies, visible and invisible. The task of moving and installing the monstrous stone sculptures was so dispiriting that several reliefs in the palace of King Sargon's successor celebrate the accomplishment. The reliefs illustrate masses of men dragging lamassu sculptures with the aid of ropes and sledges. Assyrian lamassu sculptures stand free with most of the sides shown but also function as high reliefs, in which forms emerge significantly from a surrounding background. The sculptor combined the front view of a relaxed animal with the side view of an animal in motion. The sculptor illustrated the lamassu with five legs to present a complete picture of the animal from the front and the side. The artists provided a conceptual image of the lamassu as opposed to an optical view of how the creature would actually stand in space.