The City of London (the "Square Mile", 1.12 sq mi) is the historic core and primary financial district of London, distinct from the City of Westminster (government, Buckingham Palace).
Roman Londinium → medieval trading hub → 1066 capital under William → 14th-century finance center → rebuilt after 1666 Great Fire → modern global finance capital.
Unique Corporation of London (800+ years), led by Lord Mayor, 100 elected Common Council members.
World's largest concentration of banks, insurers, investment banks; legal, accounting, consulting hub; 500,000+ jobs; major tax contributor.
Tower of London, St. Paul's Cathedral, Bank of England, Royal Exchange, Mansion House.