There are three large Pyramids of Giza; the largest of these being the Great Pyramid of Giza. There are also many other pyramids. Pyramids were built for Pharaohs. Pharaohs were the “Kings” which ruled over Egypt in ancient times. Egyptians did have the belief that death was the end, but rather a new beginning, a new journey. Egyptians believed part of the Pharaoh’s spirit would continue to be part of his remains after death. This part of the spirit was called his “ka.” For this spirit to be well-equipped in its new journey, proper measurements were taken. The body of the Pharaoh was wrapped in a way of preservation to keep the spirit safe. They believed that if the proper precautions were not met, the Pharaoh would have trouble performing his duties in the new journey. Egyptians believed that when their Pharaoh died, in this world, he would then become “King of the Dead.” This protection of his body did not end with embalming and wrapping (mummifying). The body was then placed within the pyramid for further protection, along with much of his property that he would need after he ascended to the afterlife.
The completion of the Great Pyramid of Giza (as stated previously – the largest of the Pyramids of Giza) happened around the year 2560 B.C. This “tomb” was built for the Fourth Dynasty Pharaoh named Khufu. There are three smaller pyramids that, along with the Great Pyramid create a complex of pyramids. These other three smaller pyramids were built for all of the wives of Pharaoh Khufu.
There are many theories as to how the pyramid was built, but one thing that most scientists agree on is that it was completed over the course of approximately 20 years. As to who actually built it and at what time of year, the debate continues. Some theories are of slave labor, while others believe it was built as a courtesy by all Egyptians. Some even believe that the builders were paid to build the pyramids. The Egyptians are known for their organization and documentation, so paid workers over 20 years does seem plausible.
REFERENCE: http://www.livescience.com/32616-how-were-the-eygptian-pyramids-built-.html