Plano-convex brick, Ubaid, Iraq, c 2500 BC.
© Science Museum / Science & Society Picture Library
This sun-dried, partly fired plano-convex brick is from Ubaid (early dynastic level) in present day Iraq. The first kiln-fired bricks were made in Mesopotamia in about 3200-2800 BC. Firing the bricks made them harder and much more resistant to erosion.