The Nile flows through Cairo and forms Egypt's historic heartland.
At about 6,650 kilometres, the Nile is traditionally described as the world's longest river, although measurements comparing it with the Amazon can produce different results depending on how each river's source and mouth are defined. The Nile flows northward through northeastern Africa and empties into the Mediterranean Sea.
Cairo stands on the river's banks near the beginning of the Nile Delta, where the waterway divides into distributaries and reaches the sea. Ancient Egyptian settlements, agriculture and states developed along the narrow fertile floodplain and delta beside the otherwise arid landscape.
The Nile has two principal tributaries: the White Nile, associated with the Great Lakes region of East Africa, and the Blue Nile, which rises in Ethiopia. The Aswan High Dam, completed in the 1970s, greatly changed the river's seasonal flooding and created Lake Nasser.