Gixa, Cairo, Egypt, 7 December 2010 The great Pyramids of Giza, Egypt are an iconic, ancient place of wonder and mystery. And some of the most truly iconic. To see them for the first time is a breathtaking experience. Although many ancient civilisations built pyramids, the most famous are these, counted among the largest structures ever built. The Great Pyramid of Khufu is the largest Egyptian pyramid, as well as being the only one of the Seven Wonders of the Ancient World still in existence. Here, with a murky Cairo in the background, we see the impact of air pollution on the area.