South Mumbai, colloquially SoBo from South Bombay in Indian English, administratively the Mumbai City District, is the city centre and the southernmost precinct of Greater Bombay. It extends from Colaba to Mahim and Sion neighbourhoods, and comprises the city's main business localities, making it the wealthiest urban precinct in India. Property prices in South Mumbai are by far the highest in India and among the highest in the world.

Mumbai City district is a district of Maharashtra in Konkan Division, India. As a city district, it has no headquarters or subdivisions. It, along with the Mumbai Suburban District, makes up the metropolis of Mumbai. This area is called the "Island City" or South Mumbai or Old Mumbai. It extends from Colaba in the south to Mahim and Sion in the north. The city has an area of 157 km2 (61 sq mi) and a population of 3,085,411.