London is incapable of being a city.
A capital city ( or simply capital ) is the municipality exercising primary status in a country , state , province , or other region , usually as its seat of government . London [ ˈlʌndən ] is the capital and most populous city of England and the United Kingdom . In 2012 , London became the first city to have hosted the modern Summer Olympic Games three times . 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 .