The site of this huge necropolis, which was attached to the ancient city of Memphis, includes a massive step pyramid. Built by a prolific innovator named Imhotep for the 3rd-dynasty king Dsojer (2667-2648 B.C.), the structure represents a number of important developments in engineering without which the later, and now more famous, pyramids in Giza would not have been possible.
The complex also includes a number of other tombs, with spectacular wall paintings and carvings, and the Serapeum, where the Apis bulls were interred. These bulls were considered to be the living manifestation of the god Ptah (who you will also see in wall carvings as a man wearing a tight-fitting cap and grasping an ankh), and were mummified and buried with all due ceremony.
Depending on the depth of your interest in Egyptology, you will need between an hour to half a day at the Saqqara site. There is a new museum just inside the main entrance. Though documentation is of the same unfortunate standard as most Egyptian facilities, this museum is worth a visit for orientation before you proceed up the hill to the site itself. If you're lucky enough to be here on a day with some clouds, the light on Djoser's pyramid in the hour or so leading up to sunset is spectacular. While you wander the site, you'll inevitably be approached by men who will ask if you want to see some extra tombs or sites. It is generally worth saying yes and paying about LE2 to LE5 (35¢-90¢/20p-45p).
Photography is theoretically restricted inside the tombs, but in practice the guards will accept a couple of pounds to let you do whatever you want, and the only real limit to what you do inside the tombs is your reluctance to damage irreplaceable ancient historical art with your flash or by touch.