Ancient Egyptians lived near the longest river in the world, as it provided water, food, transportation and rich alluvial mud for growing food; rainfall is almost non-existent in Egypt and flooding provided the only source of water for the crops. Its ancient name was Ar (black) because of the colour of the sediment left after the river’s annual flooding. Further away from the river was the Red Land, a region of inhospitable desert. The annual flooding is now controlled by the Aswan Dam. The Nile is therefore an essential source of life and sustenance, and has attracted an increasing number of people; a population that, together with demography, has above all developed the building industry. Cairo is one of the world’s most rapidly growing cities, with a population growing by almost two percent per year. Urban development as photographed from COSMO-SkyMed in a 7-year period. By using colours it is possible to see the changes taking place with time: no coloured urban details were found in the 2011 image. Yellow areas were built between 2011 and 2014 and Red areas were built after 2014.