The Great Pyramid of Giza in Egypt was the largest of Egypt's great pyramids. It was completed more than 4,500 years ago and is the only one of the Seven Wonders of the World that still stands today [source: Brier].
When completed, the Great Pyramid of Giza was more than 480 feet (146 meters) high. The structure is made of more than 2.3 million limestone blocks weighing about 5,500 pounds (2,495 kilograms) each. The pyramid was by far the tallest structure in ancient times and remained the tallest structure in the world for 3,800 years. When the Lincoln Cathedral was built in London, it soared only about 44 feet higher than the Giza pyramid.
Each of the blocks originally was covered with an outer casing of lustrous white limestone. This layer was later removed and used to build the city of Cairo. After this, the Pyramid's height was reduced by about 30 feet (9.1 meters). Scholars still debate how laborers may have reached the top of the pyramid, particularly hauling the heavy blocks and beams that made up the structure. They likely hauled the blocks from Aswan on huge barges.
The engineers and laborers at Giza managed to complete the build of the pyramid itself in about 30 years, which is pretty remarkable considering the lack of machinery and ambitious nature of the project. It was solid, with a virtually level base; each corner was nearly exactly 90 degrees. When Greek historian Herodotus visited the pyramids in 450 B.C., he was one of many historians who tried to solve how ancient Egyptians managed to haul blocks of such massive size to such great heights. He stated that 100,000 people worked on the structure, but modern scholars place the number at closer to 20,000 to 30,000 [source: PBS]. They most likely worked in shifts of sorts, rotating in and out of the labor force that did the heavy lifting, so to speak.
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