This study considers the urban characteristics of the old city of Fallujah and the impact of the prevailing climatic characteristics on its construction. In particular, this study focuses on the suitability of the construction methods and materials for a desert region characterized by high temperatures and a lack of rain. The researcher relied on the analytical and descriptive methodologies to reach the research objective. This study concludes that the hot arid conditions encouraged the construction of converging residential dwellings and narrow, twisted streets, designed to produce the largest area of shadows and thereby reduce the air temperature in these areas. The same purpose also contributed to the height of roofs and the selection of building materials used in the construction of walls and ceilings, as well as the distribution of spaces within the housing units.