Egypt is located in northeast Africa, bounded by the Mediterranean Sea to the north. Population is concentrated along the banks of the Nile River, especially in the Nile delta dominated by the large city of Cairo. Civilization has relied on Nile-based irrigation since ancient times. Pharaohs ruled ancient Egypt dating to 3000 BC, and their immense pyramid constructions have awed visitors ever since. This is the most heavily populated Arab-speaking country.