The Uraeus is the stylized, upright form of an Egyptian cobra, used as a symbol of sovereignty, royalty, deity and divine authority in ancient Egypt. The Uraeus is a symbol for the goddess Wadjet. She was one of the earliest Egyptian deities and was often depicted as a cobra, as she is the serpent goddess. The center of her cult was in Per-Wadjet, later called Buto by the Greeks. She became the patroness of the Nile Delta and the protector of all of Lower Egypt. The pharaohs wore the uraeus as a head ornament: either with the body of Wadjet atop the head, or as a crown encircling the head; this indicated Wadjet's protection and reinforced the pharaoh's claim over the land. In whatever manner that the Uraeus was displayed upon the pharaoh's head, it was, in effect, part of the pharaoh's crown. The pharaoh was recognized only by wearing the Uraeus, which conveyed legitimacy to the ruler. There is evidence for this tradition even in the Old Kingdom during the third millennium BCE.