London is the political, economic and cultural capital of Britain. The city grew from three distinct centers: the walled settlement founded by the Romans on the banks of the Thames in the 1st century CE, today known as the City of London, “the Square Mile,” or simply “the City”; facing it across the bridge on the lower gravels of the south bank, the suburb of Southwark; and a mile upstream, on a great southward bend of the river, the City of Westminster.
During the nineteenth century and the early parts of the twentieth-century manufacturing industries held the dominant economic position. Today service industries, especially financial and business services are now the dominant economic sector. Financial and business services account for about £15.5 billion of the £37 billion annual export of goods and services.
Numerous banks and financial institutions can be found in London. The city has the maximum number of foreign banks in any city. The city is also a major center for forex trade and trades more US dollars than New York does, and more Euros than all other cities in Europe combined. London is not just a financial city. The arts, fashion, film, media, design, law and computing industries also thrive in the city. E-commerce and related industries rank amongst the fastest growing sectors in the city's economy. Tourism is also a very important sector in the city’s economy.
Today, London is the center of operations for almost two out of every three Fortune 500 companies and the European hub for one out of every three large global conglomerates. Several well-known businesses such as HSBC, Barclays Bank, Virgin, BBC and many others have their headquarters in London. The London Stock Exchange is the largest in the world and accounts for about 32 percent of all global transactions.