London is a city.
London . Since at least the 19th century , `` London '' has also referred to the metropolis around this core , historically split between Middlesex , Essex , Surrey , Kent , and Hertfordshire , which today largely makes up Greater London , See also : Independent city § National capitals . London is a leading global city in the arts , commerce , education , entertainment , fashion , finance , healthcare , media , professional services , research and development , tourism , and transportation . Its estimated mid-2015 municipal population ( corresponding to Greater London ) was 8,673,713 , the largest of any city in the European Union , and accounting for 12.5 % of the UK population . A metropolis ( [ mᵻˈtrɒpəlɪs , _ - plɪs ] ) is a large city or conurbation which is a significant economic , political , and cultural center for a country or region , and an important hub for regional or international connections , commerce , and communications .