Some of the earliest graves for Egyptians were very simple and could easily be broken into and robbed. Then, to prevent this they started to build tombs called mastabas. These mastabas were rectangular buildings that were built over burial chambers. The pharaohs had their mastabas built with many rooms so that the burial chamber wouldn't be found by tomb robbers. Usually the graves were still robbed though. The first pyramid was a step pyramid with six steps built for Pharaoh Koser at Sakkara. Later, pyramids were built without steps, like the pyramids at Giza. The largest of these is the Great Pyramid, built for Pharaoh Khufu. Each side was 450 ft. high and 756 ft. at the base. It would have taken at least twenty years to build.