The most famous pyramids are the Egyptian pyramids — huge structures built of brick or stone, some of which are among the world's largest constructions. They are shaped as a reference to the rays of the sun. Most pyramids had a polished, highly reflective white limestone surface, in order to give them a shining appearance when viewed from a distance. The capstone was usually made of hard stone - granite or basalt - and could be plated with gold, silver, or electrum and would also be highly reflective.