Cairo, the capital of Egypt, boasts a population of over 20 million in its metropolitan area. As the largest city in the Arab world, it serves as the central hub of Islamic culture. Situated on the banks of the Nile River, Cairo thrives thanks to the nourishing waters of the Nile, a sentiment echoed by the historian Herodotus, who poetically referred to Egypt as the "fruit of the Nile." The oldest part of the city known as Historic Cairo has been designated as a World Heritage Site.