In the lower right of the main images is Tehran, the capital and largest city in Iran. The plain Tehran lies in is like a bowl. High mountains are to the north, and the hills of Kahrizak are to the south. Tehran is far from any major river and relies on water supplies located at a distance from the city. In this series of images, the expansion of the city extends in all directions, especially north toward the mountains. Tehran’s population in 1986 was about 6 million. It has grown to almost 13.8 million in 2021.