Linguistic fun!

So here's a little bit of etymology trivia from my Linguistics course on the history of English:

The Romans often Latinized Celtic placenames in England, rather than invent new ones. For example, London was a Celtic placename based on the personal name Londinos ("the brave one"); the Romans eventually changed it to "Londinium." Obviously, this name didn't last.

However, Lancaster is one of the few cities in England to retain a Latin element: "Lan" is the Celtic name of the River Lune, whereas "castra" is the Latin word for camp/walled town. So, "Lancaster" means something like "walled camp on the River Lune."