In Egyptian architecture, to which belong some of the earliest extant structures to be called architecture (erected by the Egyptians before 3000 B.C.), the post-and-lintel system was employed exclusively and produced the earliest stone columnar buildings in history. The architecture of W Asia from the same era employed the same system; however, arched construction was also known and used. The Chaldaeans and Assyrians, dependent upon clay as their chief material, built vaulted roofs of damp mud bricks that adhered to form a solid shell.
After generations of experimentation with buildings of limited variety the Greeks gave to the simple post-and-lintel system the purest, most perfect expression it was to attain (see Parthenon; orders of architecture). Roman architecture, borrowing and combining the columns of Greece and the arches of Asia, produced a wide variety of monumental buildings throughout the Western world. Their momentous invention of concrete enabled the imperial builders to exploit successfully the vault construction of W Asia and to cover vast unbroken floor spaces with great vaults and domes, as in the rebuilt Pantheon (2d cent. A.D.; see under pantheon).