The Egyptians were one of the first major civilisations to codify design elements in art and architecture. Egyptian blue, also known as calcium copper silicate is a pigment used by Egyptians for thousands of years. It is considered to be the first synthetic pigment. The wall paintings done in the service of the Pharaohs followed a rigid code of visual rules and meanings. Egyptian civilisation is renowned for its colossal pyramids, temples and monumental tombs. Well-known examples are the Pyramid of Djoser designed by ancient architect and engineer Imhotep, the Sphinx, and the temple of Abu Simbel. Modern and contemporary Egyptian art can be as diverse as any works in the world art scene, from the vernacular architecture of Hassan Fathy and Ramses Wissa Wassef, to Mahmoud Mokhtar's sculptures, to the distinctive Coptic iconography of Isaac Fanous. The Cairo Opera House serves as the main performing arts venue in the Egyptian capital.