The Giza Necropolis is found on the Giza Plateau, eight km inland into the desert from the old town of Giza on the Nile, some 20 km southwest of Cairo city centre. This Ancient Egyptian cemetery consists of 3 main pyramids i.e; the largest (146 m) of which is the Pyramid of Khufu (a.k.a the Great Pyramid, Pyramid of Cheops), the Pyramid of Khafre (or Chephren) is smaller (136 m tall, 215 m base), and the Pyramid of Menkaure (or Mykerinus) is the most modestly sized (62 m tall, 105 m base) out of the three. There are also a number of smaller satellite edifices, known as "queens" pyramids, causeways, valley pyramids and the Great Sphinx. The Great Pyramid of Giza is the oldest and last remaining of the Seven Wonders of the World. It took 20 years to build, construction is believed to have finished around 2560 BC. The plans were drawn up by Khufu's vizier, Hemon. Khafre's pyramid is was completed around 2532 BC, at the end of Khafre's reign. Unlike the Great Pyramid, and Menkaure's Pyramid, Khafre's Pyramid retains some of its smooth limestone casing at its apex. It also appears larger than the adjacent Khufu pyramid because it stands on higher ground and the steeper angle of inclination of its construction. However, in truth, it is smaller in both height and volume. Menkaure's Pyramid was built to serve as the tomb of the fourth dynasty Egyptian Pharaoh Menkaure but its date of construction is unknown, because Menkaure's reign has not been accurately defined. Robert Bauval and Adrian Gilbert proposed that the three main pyramids at Giza form a pattern on the ground that is virtually identical to that of the three belt stars of the Orion constellation. Another interesting belief about the Giza pyramids is that the longitude passing through them divides the earth's landmass into two exact halves.