The biggest pyramid in the world is the Great Pyramid of Giza. Archeologists believe that it was built for Fourth Dynasty Egyptian Pharaoh Khufu and was completed in 2560 BC. The pyramid has lost its outer casing of highly polished stones with the rough hewn stones remaining. The casings were shaken loose from the structure in 1301 AD. The pieces that fell were used to build mosques and other buildings in Cairo that are still there today. Some of the casings remain at the site as a testament to the great craftsmanship that went into building this giant.
What is truly marvelous about this building is the precise math involved in its construction. The foundation is only one minute (1 degree = 60 minutes). The four sides are perfectly aligned with true North, South, East and West. The ground at the base is flat to within 15 millimeters. What is truly amazing is that although the Egyptians didn’t know the value of π, they used the number in their calculations because the height and width of each side’s proportions are to within a 0.05% margin from 2π.
The Great Pyramid of Giza is the only remaining structure of the Seven Wonders of the Ancient World. Just in case you are curious, the other six wonders are The Hanging Gardens of Babylon, the Statue of Zeus at Olympia, the Temple of Artemis at Ephesus, the Mausoleum of Maussollos at Halicarnassus, the Colossus of Rhodes, and the Lighthouse of Alexandria. Most of them were destroyed by earthquakes.