Johannesburg (/dʒoʊˈhænɪsbɜːrɡ/joh-HAN-iss-burg, US also /-ˈhɑːn-/-HAHN-, Afrikaans:[jʊəˈɦanəsbœrχ]; Zulu and Xhosa: eGoli[ɛˈɡɔːli]; colloquially known as Jozi, Joburg, Jo'burg or "The City of Gold") is the most populous city in South Africa. The City of Johannesburg itself has a population of 5,538,596, while the greater urban agglomeration exceeds 14.8 million, making it a megacity and one of the 100 largest urban areas in the world. Johannesburg is the provincial capital of Gauteng, the wealthiest province in South Africa, and seat of the country's highest court, the Constitutional Court. Situated in the mineral-rich Witwatersrand hills, the city has long been at the epicentre of the international mineral and gold trade. The richest city in Africa by GDP and private wealth, Johannesburg functions as the economic capital of South Africa and is home to the continent's largest stock exchange, the Johannesburg Stock Exchange.
Johannesburg was established in 1886, following the discovery of gold, on what was once farmland. Within a decade, the population surged to over 100,000, driven by the large gold deposits found along the Witwatersrand. Modern Johannesburg is an amalgamation of formerly separate cities, townships and settlements, reflecting apartheid-era spatial segregation policies. Soweto ("South-Western Townships"), designated a "blacks only" city until 1994, is one of the most historically significant areas for modern South Africa. Home to key anti-apartheid leaders, including Nelson Mandela and Desmond Tutu, it became the epicenter of the 1976 Soweto Uprising, where peaceful student protests were met with brutal force. In contrast, Lenasia is predominantly populated by English-speaking Indo-South Africans (people of Indian and South Asian descent). Formerly "white-only" areas include Sandton, known as "Africa's richest square-mile", Randburg and Roodeport.
The Witwatersrand (UK: /wɪtˈwɔːtərzrænd,-rɑːnd/, US also /ˈwɪtwɔːtərz-/; Afrikaans pronunciation:[ˌvətˌvɑːtərsˈrant]; locally the Rand or, less commonly, the Reef) is a 56-kilometre-long (35 mi), north-facing scarp in South Africa. It consists of a hard, erosion-resistant quartzite metamorphic rock, over which several north-flowing rivers form waterfalls, which account for the name Witwatersrand, meaning 'white water ridge' in Afrikaans. This east-west-running scarp can be traced with only one short gap, from Bedfordview (about 10 km [6.2 mi] west of O.R. Tambo International Airport) in the east, through Johannesburg and Roodepoort, to Krugersdorp in the west (see the diagram at left below).
The scarp forms the northern edge of a 7-to-10-kilometre-wide (4–6 mi) plateau (or ridge) which rises about 200 m (660 ft) above the surrounding plains of the Highveld. A number of picturesque Johannesburg suburbs, including Observatory, Linksfield Ridge and Upper Houghton are located along the scarp, overlooking the rest of northern Johannesburg with views up to the Magaliesberg (although locals refer to segments of the scarp using area-specific names, such as Linksfield Ridge, Parktown Ridge or Observatory Ridge). The entire plateau-like structure is also often called the Witwatersrand. The plateau's elevation above sea-level is between 1,700 and 1,800 metres (5,600–5,900 ft).