The Great Pyramids of Giza were once covered in highly polished, brilliant white Tura limestone casing stones that made them glisten like diamonds under the desert sun. Over thousands of years, these outer stones were lost due to a combination of natural forces and human intervention. Severe earthquakes throughout history loosened many of the casing stones, making them easier to remove. However, the primary reason they are gone is "quarrying" by local rulers and builders. During the Middle Ages, especially under the rule of various sultans and the construction of Islamic Cairo, the smooth limestone was stripped from the pyramids and repurposed to build local mosques, palaces, and fortifications. This left the rugged, inner core of yellow-brown limestone blocks that we see today. You can still see a small remnant of the original casing at the very peak of the Pyramid of Khafre, providing a hint of how the structures once looked. Additionally, the very top of each pyramid originally featured a pyramidion—a capstone often plated in gold or electrum—which was likely the first part to be looted by ancient treasure hunters.