Nairobi is the capital and the largest city of Kenya. The name comes from the Maasai phrase Enkare Nairobi, which translates to "cool water", a reference to the Nairobi River which flows through the city. The city proper had a population of 3,138,369 in the 2009 census, while the metropolitan area has a population of 6,547,547. The city is popularly referred to as the Green City in the Sun.