The City of London (which is not a city called "London")

Inside of London is the City of London, which has roughly 11,000 residents and is enormously wealthy. This video¹ explains it all ... well, sorta, kinda. There is a Part 2 coming. While you wait you might be interested in knowing the difference between England, Great Britain, and the United Kingdom (not to mention the Crown Dependencies, the Commonwealth Realm, and the Overseas Territories).  The video is from the Smithsonian Magazine, which has great videos.
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¹  If the embedded video (which comes from the Smithsonian website) does not work well, use the link to go to YouTube.