4K 3840×2160. Bosphorus bridge connecting Asia and Europe. Turkey Istanbul city from the air plane window. Giant canal. Urbanization refers to the population shift from rural to urban areas the gradual increase in the proportion of people living in urban areas and the ways in which each society adapts to the change. Air pollution. The world’s overcrowded biggest cities. Large metropol from the air plane window. Cramped and crowded housing city. Unplanned urbanization is a great problem for metropolis like Istanbul city. Crooked urbanization.