Narrow brick walls define the outlines of a small room or courtyard in the low-lying area between L and SD Areas on the Citadel Mound. A standard size of mud brick and baked brick (7 x 14 x 28 cm) was used in house construction, and a different size (10 x 20 x 40 cm) was used in the building of platforms and city walls (see Slide 20). Both sizes of brick have identical proportions--thickness (=1), width (=2 x 1) and length (= 4 x 1). This ratio is commonly expressed as 1:2:4. The fill inside this room is filled with various types of craft manufacturing debris, including chert blade making, agate bead making, shell working, as well as many finished stone tools and beads. The white surface is a thick layer of encrusted salts.