Johannesburg is the most populous city in South Africa, classified as a megacity, and is one of the 100 largest urban areas in the world. According to Demographia, the Johannesburg–Pretoria urban area (combined because of strong transport links that make commuting feasible) is the 26th-largest in the world in terms of population, with 14,167,000 inhabitants. It is the provincial capital and largest city of Gauteng, which is the wealthiest province in South Africa. Johannesburg is the seat of the Constitutional Court, the highest court in South Africa. Most of the major South African companies and banks have their head offices in Johannesburg. The city is located in the mineral-rich Witwatersrand range of hills and is the centre of large-scale gold and diamond trade.
