Cairo is located in northern Egypt, known as Lower Egypt,  south of the Mediterranean Sea and  west of the Gulf of Suez and Suez Canal. The city lies along the Nile River, immediately south of the point where the river leaves its desert-bound valley and branches into the low-lying Nile Delta region. Although the Cairo metropolis extends away from the Nile in all directions, the city of Cairo resides only on the east bank of the river and two islands within it on a total area of . Geologically, Cairo lies on alluvium and sand dunes which date from the quaternary period.