Feyrouz Ahlam

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1. Introduction Urbanization, a growing mass and proportion of the population living in cities and towns, has been a rapid phenomenon in recent times (Annez and Buckley 2009). Less than 200 million people, representing 15% of the world’s population, lived in cities in 1900 (Zinkina et al. 2017), but the situation changed dramatically during the 20th century.