Three great cultures flourished in the Americas be. fore the arrival of the Europeans, but not all three had an equal influence on the art end architecture of succeeding generations. The Inca civilization, with its highly developed science of construction and engineering, was poor in plastic expression and never created a strong architectural art. On the other hand, the Mayan and Aztec civilizations left a rich heritage that has never completely disappeared. For the past forty years, it has been the most obvious source of inspiration for Mexican artists and architects. In order to understand the "Mexican school of art" as it has existed since 1920, it is necessary to be familiar with the most important aspects of pre-Columbian art and architecture.