The site of the principal necropolis of the ancient city of Memphis, near Cairo, Egypt, used from the 2nd Dynasty to the Christian period. There are 15 royal pyramids, mainly of the Old Kingdom (c 2575-2130 BC), the most being the Step Pyramid erected by Imhotep for Djoser, pharaoh of the 3rd dynasty, c 2630 BC. The royal mastaba tombs of the nobility making up most of the cemetery have yielded much evidence on the Archaic Period. Also buried here, at the Serapeum, were the sacred Apis bulls. With the passage of time burial chambers were more massively constructed of stone, and eventually hewn from solid rock. There are a large number of important private tombs of the Archaic through the Graeco-Roman period.