Nairobi ( ny-ROH-bee) (Jiji kuu la Nairobi, in Swahili) is the capital and largest city of Kenya, located in the south-central part of the country. As of 2026, it has a population of 5.6 million and a metropolitan population of 15.95 million, making it the 8th most populous city in Africa and the 4th most populous metropolitan area. The city goes beyond its borders and has expanded into neighbouring counties, making it the 4th largest metropolitan area in Africa.
Nicknamed the "Green City under the Sun", Nairobi is uniquely notable for being the only capital city in the world that hosts a national park within its boundaries. Its name originates from the Maasai phrase Enkare Nyirobi, meaning "place of cool waters".
As the national capital, Nairobi is home to the Kenyan Parliament Buildings, the State House and the Supreme Court Building. It is the major financial and economic hub of East Africa, hosting thousands of Kenyan businesses and international companies and organisations, including the United Nations Environment Programme (UN Environment) and the United Nations Office at Nairobi (UNON). The Nairobi Securities Exchange (NSE) is one of the largest stock exchanges in Africa and the second-oldest exchange on the continent. It is Africa's fourth-largest stock exchange by trading volume, capable of processing 10 million trades a day. Nairobi is considered a global city and was ranked as a "Beta World City" by the Globalisation and World Cities Research Network as of 2024.
Nairobi was founded in 1898 by colonial authorities in British East Africa, as a rail depot on the Uganda–Kenya Railway. The authorities favoured it as an ideal resting place due to its high elevation, temperate climate, and adequate water supply. 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. During Kenya's early period, the city became a centre for the coffee, tea and sisal industries. Successive post-independence governments have built and turned Nairobi into a modern metropolitan city with a diverse population and a growing economy.
The site of Nairobi was originally a swamp land occupied by a pastoralist people, the Maasai, the long-distance trader community, Akamba People, as well as the agriculturalist Kikuyu people. The name Nairobi comes from the Maasai expression meaning 'cool waters'. referring to the cold water stream which flowed through the area. With the arrival of the Uganda Railway, the site was identified by Sir George Whitehouse for a store depot, shunting ground and camping ground for the Indian labourers working on the railway.
Whitehouse, chief engineer of the railway, favoured the site as an ideal resting place due to its high elevation, temperate climate, adequate water supply and being situated before the steep ascent of the Limuru escarpments. His choice was criticised by officials within the Protectorate government who felt the site was too flat, poorly drained and relatively infertile.
In the pre-colonial era, the people of modern Kenya mostly lived in villages amongst their tribes and cultural groups, where they had rulers within their communities rather than one singular government or leader.
In 1898, Arthur Church was commissioned to design the first town layout for the railway depot. It constituted two streets – Victoria Street and Station Street, ten avenues, staff quarters and an Indian commercial area. The railway arrived at Nairobi on 30 May 1899, and soon Nairobi replaced Machakos as the headquarters of the provincial administration for the Ukamba province.
On the arrival of the railway, Whitehouse remarked that "Nairobi itself will in the course of the next two years become a large and flourishing place and already there are many applications for sites for hotels, shops and houses." The town's early years were however beset with problems of malaria leading to at least one attempt to have the town moved. In the early 1900s, Bazaar Street, now Biashara Street, was completely rebuilt after an outbreak of plague and the burning of the original town.
Between 1902 and 1910, the town's population rose from 5,000 to 16,000 and grew around administration and tourism, initially in the form of big game hunting. In 1907, Nairobi replaced Mombasa as the capital of the East Africa Protectorate. In 1919, Nairobi was declared to be a municipality.
In 1921, Nairobi had 24,000 residents, of which circa 12,000 were native Africans. The next decade saw growth in native African communities in Nairobi, and they began to constitute a majority for the first time. This growth caused planning issues, described by Thorntorn White and his planning team as the "Nairobi Problem". In February 1926, colonial officer Eric Dutton passed through Nairobi on his way to Mount Kenya, and said of the city:
Maybe one day Nairobi will be laid out with tarred roads, with avenues of flowering trees, flanked by noble buildings; with open spaces and stately squares; a cathedral worthy of faith and country; museums and art; theatres and public offices. And it is fair to say that the Government and the Municipality have already bravely tackled the problem and that a town-plan ambitious enough to turn Nairobi into a thing of beauty has been slowly worked out, and much has already been done. But until that plan has borne fruit, Nairobi must remain what she was then, a slatternly creature, unfit to queen it over so lovely a country.
After World War II, continuous expansion of the city angered both the indigenous Maasai and Kikuyu. This led to the Mau Mau Uprising in the 1950s, and the Lancaster House Conferences, which initiated a transition to Kenyan independence in 1963.
In the spring of 1950, the East African Trades Union Congress (EAUTC) led a nine-day general strike in the city.
Nairobi remained Kenya's capital after independence, and its continued rapid growth put pressure on the city's infrastructure, with power cuts and water shortages becoming a common occurrence.
In September 1973, the Kenyatta International Conference Centre (KICC) was opened to the public. The 28-story building at the time was designed by the Norwegian architect Karl Henrik Nøstvik and Kenyan David Mutiso. It is the only building within the city with a helipad that is open to the public. Of the buildings built in the Seventies, the KICC was the most eco-friendly and most environmentally conscious structure. Its main frame was constructed with locally available materials like gravel, sand, cement and wood, and it had wide open spaces which allowed for natural aeration and lighting. Cuboids made up the plenary hall, the tower consisted of a cylinder composed of several cuboids, and the amphitheatre and helipad both resembled cones. The tower was built around a concrete core, and it had no walls but glass windows, which allowed for maximum natural lighting. It had the largest halls in eastern and central Africa.
In 1972, the World Bank approved funds for further expansion of the then Nairobi Airport (now Jomo Kenyatta International Airport), including a new international and domestic passenger terminal building, the airport's first dedicated cargo and freight terminal, new taxiways, associated aprons, internal roads, car parks, police and fire stations, a State Pavilion, airfield and roadway lighting, fire hydrant system, water, electrical, telecommunications and sewage systems, a dual carriageway passenger access road, security, drainage and the building of the main access road to the airport (Airport South Road). The cost of the project was more than US$29 million, US$111.8 million in 2013 dollars. On 14 March 1978, construction of the terminal building was completed on the other side of the airport's single runway and opened by President Jomo Kenyatta less than five months before his death. The airport was renamed Jomo Kenyatta International Airport in memory of its first president.