Nairobi (/naɪˈroʊbi/) 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 4,397,073 in the 2019 census, while the metropolitan area has a population of 9,354,580. The city is popularly referred to as the Green City in the Sun.
Nairobi was founded in 1899 by the colonial authorities in British East Africa, as a rail depot on the Uganda Railway. The town quickly grew to replace Mombasa as the capital of Kenya in 1907. After independence in 1963, Nairobi became the capital of the Republic of Kenya.