“All the pyramids were covered with a fine white limestone,” explains the scientist. This coating gave the pharaohs mighty tombs a smooth finish, reflecting sunlight.

Originally, the Great Pyramids of Giza were not the rough, sandy grey-brown stones we see today; they were a brilliant, shimmering white. When they were first completed over 4,500 years ago, they were encased in a layer of highly polished "casing stones" made of Tura limestone. These stones were cut with extreme precision to create a smooth, flat surface that would reflect the intense Egyptian sun, making the structures glow like white beacons across the desert. At the very top, many believe they were crowned with a "pyramidion" (capstone) often covered in electrum—a mix of gold and silver. Over the millennia, most of these white casing stones were stripped away by various rulers to build mosques and palaces in nearby Cairo, or were loosened by earthquakes. Today, you can only see a small remnant of this original white limestone casing at the very peak of the Pyramid of Khafre, giving us a glimpse of how pristine and bright the structures once appeared.