Imhotep, King Djoser's architect, created the first pyramid in 2780 B.C. by stacking six mastabas, each smaller than the one underneath, to make a pyramid rising in stages. This Step Pyramid is located near Memphis on the west bank of the Nile River in Sakkara. It is one of the oldest monuments in Egypt. The ancient Egyptians believed that death was the end of life and that the soul needed a body to live after death. Therefore, they built pyramids for their dead kings so that their souls could live there also. Sometimes many thousands of slaves were killed and their bodies used to build the pyramid of the king. The Egyptians made great efforts to ensure that their kings would be buried with great pomp and ceremony. They even built larger pyramids over older ones to accommodate more treasure. The largest pyramid in existence is that of Khufu (or Cheops as he was called in Greek), who reigned from 2589 to 2566 B.C. It is two miles long and covers about five acres! It needs ten thousand men to lift it into place every year during the rainy season when water levels in the Nile River are high. Pyramids have been built in other parts of the world, but none are as large or as famous as those in Egypt.