A monumental tomb in the shape of a pentahedron, a square base and four straight sides converging to an apex, built by the ancient Egyptians in stone or brick to cover or contain the burial chamber of a pharaoh. Its origin lay in the mudbrick mastaba of the Archaic Period, which in the Old Kingdom became more elaborate with the use of stone, regularity of shape, and larger size. It evolved from the step pyramid as seen at Sakkara, Dahshur, and Meidum. The pyramid is the central monument in a pyramid complex and was the preferred tomb in the Old and Middle Kingdoms (3rd-12th Dynasties). The largest and most famous is the Giza group and Khufu's is the biggest with a 230 meter long base and original height of 146 meters. The elaborateness of the funerary ritual, witnessed by the mortuary temples attached to all pyramids, had the same purpose, of guaranteeing the eternal well-being of the deceased. This sepulchral chamber having been connected with the upper world by a passage sloping downwards from the north, the graduated structure was regularly built over it, the proportions of the base to the sides being constantly preserved. The building was continued during the lifetime of its destined tenant, and covered and closed immediately upon his death. The construction of the pyramids as early as the 26th century BC was an extraordinary achievement of engineering and architecture. The tradition of the pyramid as a royal tomb was revived by the kings of Napata and Meroe. In Mesopotamia, Mesoamerica, and South America, pyramids were used as temple-platforms. There are over 80 pyramids in Egypt and ancient Nubia (Sudan).