History of the Pyramids of Giza

It took more than 80 years and roughly 20,000 to 30,000 workers to build the pyramids of Giza. Scientists believe they were built while the Nile River was flooded. That made it possible for limestone blocks to be floated from the quarries to the base of the pyramid. The stones were then polished and pushed up ramps into position. But manual laborers weren't the only ones who helped build the pyramids. Architects ran ropes from the outer corners up to the planned summit to make sure the stones were positioned correctly. And since the pyramids are highly spiritual to the Egyptians, priests and astronomers carefully selected the right orientation for each one.

The Pyramid of Khufu is sometimes called the Great Pyramid, because at 481 feet tall, it's the largest of the three Giza pyramids. It's also the last of the Seven Wonders of the Ancient World still standing. The pyramid was built around 2550 B.C. by Pharaoh Khufu. It consists of about 2.3 million stone blocks, weighing an average of 2.5 to 15 tons each. The Great Pyramid has three burial chambers: the first underground, the second above ground and the third acted as the king's chamber. During the time of its construction, the Great Pyramid was the centerpiece of an amazing compound that, according to National Geographic, "included several small pyramids, five boat pits, a mortuary temple, a causeway, a valley temple, and many flat-roofed tombs for officials and some members of the royal family."

The Pyramid of Khafre was built around 2520 B.C. and stands 471 feet high. Though Khafre's pyramid is smaller than his father Khufu's, Khafre made up for it by including an elaborate complex which boasts a mortuary temple, niches for royal statuary, an entrance hall, storage chambers, a colonnaded courtyard and an interior sanctuary. It also has more statues than any other pyramid, the most notable of which is the great Sphinx. The Sphinx is carved from bedrock and stands in front of Khafre's pyramid. It depicts the pharaoh as a human-headed lion, wearing the headdress of the pharaohs.

The last of the three great pyramids, the Menkaura Pyramid is a lot smaller than the others. Built around 2490 B.C., archeologists believe the Menkaura Pyramid is smaller because there wasn't enough room left at the Giza Plateau and also because the cost of building pyramids had risen so much by that time. Also, Egypt was beginning what we would call an economic recession. While the other Great Pyramids were made of limestone, Menkaure's pyramid was covered in granite on the bottom levels and in the burial chamber.

Today, the Pyramids are a frequented tourist attraction, with more than a million visitors annually.