City of London
The City of London, as distinct from London, is a small area at the heart of London, occupying the site of Roman Londinium and forming the core of the medieval city. It has a population of just 9,200 (2005 est) and an area of 1 sq mile (2.6 km2) but is a highly important district as it encompasses most of London's main financial institutions; indeed, the term 'the City' is often used to describe the UK financial sector (as is another term, 'the square mile', referring to the area of the City). This usage has, confusingly, continued even though a significant proportion of the financial sector is now based in Canary Wharf, several miles out from the City.
From the sixteenth century onwards London began to expand rapidly in all directions, while the Corporation of the City of London continued to rule just over its original domain; from the nineteenth century it began to adopt its special financial character, and its population began to drop steeply. Today, in terms of population, it is the second smallest of English cities, and while scores of thousands of workers travel to the City daily, on Sundays its deserted streets feel like those of a remarkably opulent ghost town.
The City of Westminster, the other major historical heart of London, is located west of the City of London.