Small building unit in the form of a rectangular block, first produced in a sun-dried form at least 6,000 years ago. Clay, the basic ingredient, is mined from open pits, formed, and then fired in a kiln to produce strength, hardness, and heat resistance. Brick was the chief building material in the ancient Near East. Its versatility was expanded in ancient Rome by improvements in manufacture and by new techniques of bonding. Brick came to be widely used in Western Europe for the protection it offered against fire. See alsomasonry, mortar.