Large scale urban fires which may accompany natural disasters or result from war-time actions are explored. The literatures pertaining to the macroscopic physics of large area fires is reviewed and analyzed, and areas where current understandings are deficient are identified. Features specific to a nuclear-weapon- initiated city fire are considered in detail. Based on hydrodynamic and thermodynamic principles, a self-consistent physical model is constructed which accounts for the unique properties of large ares fires. Due to the scale of such events, a significant perturbation to the atmosphere results and a recirculation flow field is established. This accounts for the high velocity winds characteristic of firestorms observed in WW II fire bombings. Development of the governing equations shows that the urban area interactions are principally inviscid. Based on a component model, scalings suitable for formulation of small scale experiments are derived. Recommendations for future experimental and theoretical modeling studies are made in areas that would aid in emergency management of large scale fires and in dealing with disasters in which uncontrolled fire may play an important role (e.g., earthquakes, nuclear warfare, revolution).