The Great Pyramid (or the pyramid of Cheops), the largest of the three Giza pyramids, was completed in 2600 B.C. The pyramid was built by king Khufu and it clearly represented the culmination of the efforts of the ancient Egyptians. This, in many respects, is due to the perfection of its architecture, and planning. It is quite astonishing that we do not know a lot about Khufu, who ordered building that pyramid to be the eternal settlement for his body. The Great Pyramid once stood at 146m but is now 137m tall. The length of each side of its square base was originally 230m, but now it has become 227m as a result of the erosion of many surface stones. Estimations concluded that it took about 100,000 men to build this pyramid using approximately 2.5 million stone blocks each weighing from 2.5 to 15 tons. The three sides of the pyramid used to be smooth made of polished stone. Now, as a result of weather erosion, this smooth surface no longer exists. Instead, the surface now appears to have a rough texture. The original entrance of the pyramid (not used nowadays) is in the middle of the northern side, about 20m above the ground. The present entrance lies below and to the west of the original one. This entrance leads to different passages and corridors leading to the main room which is called " The King's Room". The ceiling and the floor of this room (which is 5.2mx10.8m) are made of red granite. It has a straight ceiling made up of 9 huge blocks, each weighing nearly 50 tons. Furthermore, in the western part of the room, we can find a huge granite coffin without a lid and void of inscriptions.