Africa boasts one of the world's richest cities that stands comparison with other financial metropolises such as London or New York.

       Often known as the City of Gold, Johannesburg in South Africa is officially the continent's wealthiest city.

       According to the Henley & Partners Africa Wealth Report, over 12,000 millionaires, 25 centi-millionaires (worth ￡100 million or more), and two billionaires live there.

       The discovery of gold in the 19th century transformed the city's fortunes, turning it into an economic powerhouse.

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       It was an Australian gold prospector George Harrison, who first discovered deposits of the precious metal under the Witwatersrand hills in 1886.

       His discovery led to a gold rush as fortune seekers descended in large numbers in the area.

       The large deposits of the precious metal precipitated the Anglo-Boer War of 1899-1902, in which the British fought the Boers for control of the then Transvaal and its gold.

       Even today, gold mining remains a big part of the city's identity. Just southwest of Johannesburg sits the Mponeng gold mine - the deepest mine in the world.

       It reaches an incredible 2.2 miles (3.84 kilometres) below the Earth's surface, and plans are underway to extend it even further.

       At that depth, the temperature soars, and conditions are extreme, but Mponeng continues to produce vast amounts of gold, with reserves of over 46 million ounces.

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       Johannesburg has a population of more than six million people, covers an area of some 1 700km2 and is home to one of Africa's tallest buildings - the 50-storey Carlton Centre.

       Its economy is booming, with industries like finance, IT, and manufacturing driving growth.

       Most of Johannesburg's wealth is centred in Sandton, an upscale area often described as "the richest square mile in Africa".

       Sandton is home to luxury shopping centres, five-star hotels, and the Johannesburg Stock Exchange (JSE), Africa's largest stock market.