The Witwatersrand gold rush began in 1886 when prospector George Harrison found gold on a farm outside what is now Johannesburg. Within three years, 100,000 people had arrived; within a decade, the city was South Africa's largest. The gold lay deep underground, requiring industrial mining that only large corporations could afford; the companies that emerged - later merged into Anglo American and others - became the foundations of South African economic power.

The mining employed hundreds of thousands of workers, mostly Black South Africans housed in single-sex hostels near the mines, their families left in rural homelands. The racial geography that apartheid would formalize began with the mines: white managers in leafy suburbs, Black workers in compounds and townships, the segregation built into the city's foundation. The mines have largely closed now, but the wealth they generated built Johannesburg's skyline and shaped its inequalities.

Soweto - South Western Townships - began as a collection of settlements for Black workers excluded from Johannesburg proper. By 1976, when students protesting the mandatory use of Afrikaans in schools faced police bullets, Soweto had become a city of over a million, invisible to white South Africans who never visited but essential to the economy they dominated. The Soweto Uprising, which killed hundreds of protesters and sparked international outrage, began apartheid's end.

Soweto is now officially part of Johannesburg, its residents technically free to live anywhere they can afford. The practical reality is more complicated: the townships remain poor, the suburbs remain largely white, the geographic apartheid persisting through economics rather than law. Mandela's former home on Vilakazi Street is now a museum; the Hector Pieterson Memorial commemorates the 12-year-old killed in the uprising. Soweto offers township tourism, visitors riding through neighborhoods that apartheid created, the poverty that inequality maintains now a destination.

Johannesburg's inner city has experienced one of the world's most dramatic urban transformations. The high-rises built for white businesses in the 1960s and 1970s emptied as apartheid ended and white residents fled to the northern suburbs. The buildings became hijacked - occupied by informal tenants who converted offices to housing, the elevators failing, the services collapsing, the crime and decay that defined inner-city Johannesburg's reputation.

The revival began slowly. The Maboneng precinct, developed in the 2010s, converted factories to apartments and galleries, creating a neighborhood that hipsters and artists populated. Constitution Hill, where Mandela and Gandhi were both imprisoned, became a museum complex anchored by the Constitutional Court. The inner city remains dangerous in parts, vibrant in others, a contested space where South Africa's future is being improvised. The transformation is incomplete but real.

The northern suburbs - Sandton, Rosebank, Hyde Park - hold the wealth that fled the inner city. Sandton City mall, anchored by the Johannesburg Stock Exchange, represents the concentration of capital that apartheid's geography created and post-apartheid economics has not redistributed. The suburbs are leafy, walled, secured by private security companies that employ more guards than the police force.

The suburbs are not all white anymore - the Black middle class that emerged after 1994 has moved north, creating diversity within privilege. But the inequality that defines South Africa is visible from any elevated point: the swimming pools and gardens of the north, the informal settlements of the south and east, the distance between them crossed by workers who commute daily to serve those who can afford them. The suburbs offer what wealth offers everywhere, purchased with money that the mines and markets generated.

Johannesburg should not work. The infrastructure is failing; the power grid cannot meet demand; the crime rates would empty other cities; the inequalities would spark revolution elsewhere. Yet the city persists, grows, adapts. The informal economy that statistics cannot measure generates livelihoods; the entrepreneurs who cannot access formal finance create businesses anyway; the resilience that survival requires becomes the city's character.

The future is uncertain. The mines that created Johannesburg are exhausted; the manufacturing that replaced them faces competition; the service economy requires skills that unequal education has not provided. Yet Johannesburg remains South Africa's economic center, the place where opportunity concentrates even when opportunity is limited. The city that gold built must find new foundations; the process of finding them is what makes Johannesburg vital, even as it remains troubled.