Greater London is often referred to as "the City" or "the Square Mile" and it forms the main financial district. Archaically, the urbanised area of London was known as the Metropolis. In common usage, the terms "London" and "Greater London" are usually used interchangeably. Greater London is officially divided for some purposes, with varying definitions, into Inner London and Outer London. For some strategic planning purposes it is divided into five sub-regions. Greater London is under the strategic local governance of the Greater London Authority (GLA). It consists of an elected assembly, the London Assembly, and an executive head, the Mayor of
Financial District, San Francisco Square. To the east lies the Embarcadero waterfront and the Ferry Building. To the south lies Market Street and the South of Market district. The Financial District is served by more than two dozen Muni bus and rail lines, including one cable car line, as well as Montgomery Street Station and Embarcadero Station in the BART system. The nickname "FiDi" is occasionally employed, analogous to nearby SoMa. The area is commonly referred to as "Downtown" as well, although "Downtown" may include the broader Union Square, Chinatown, Tenderloin, and SoMa districts as well. The District is home to numerous corporate headquarters,