The effect of natural disasters in establishing new settlements in Egypt is aggravated by the often- noted lack of environmental awareness, insufficiency of warning system, virtual lack of capacity for recognition of hazards, and lack of infra- structures for disaster mitigation. The present study deals with hazards that have occurred already in Al-Mokattam and 15th May City areas and provides recommendations to minimize future risks.Groundwater can be a problem in desert areas, especially if its level is rising. In our study we are adressing such issues by microgravity investigation in the Urban center of Al-Mokattam area and 15th May City in great Cairo. The presence of this groundwater beneath some of the buildings work as a good environment for clay minerals and halite to react, causing subsurface cavities. These cavities are formed by dissolution processes in limestone and salt rocks, and lead to restrictions in land utilization and pose hazards to development and engineering processes. The existence of subsurface cavities is a serious problem in these areas, where road and highway subsidence, building foundation collapse due to problems associated with subsurface cavities. Detection and delineation of subsurface cavities remains a common task in the studied areas. Microgravity surveys for cavity detection are applied and the two- dimensional gravity modeling along three profiles was performed, one on G .Al-Mokattam (West of Salah Salem Road) and two others are selected in 15th May City ( in Megawra 14). The results of these final models provide reasonable image of the main cavities and its extension in the studied areas.