The Canadian province of British Columbia, between the metropolis of Vancouver and its vast mountain forests and oceans nearby, has become the third-largest film production center in North America thanks partly to its ability to stand in for the Pacific Northwest (usually Seattle or Portland) or any small, rural town in the northern half of the US.
In many cases, the average viewer may not be familiar with the location in question, but it can end up bugging those viewers who have been or actually in those locations.
Also take into account that any production wants to Shoot the Money, and may choose a more scenic place to film instead of the less impressive place it actually is. For those who live in southern California, it is amusing to point out places one recognizes from TV shows.
This can have a very odd effect the first time one southern California. The most used location is Griffith Park, whose scrabble mountains can be seen in nearly every 1950's "jungle" movie and .
While obviously it might be a bit difficult filming an ancient Rome in Rome itself, as the city resembles Caesar's city in name only, even the London of today is quite different from the London of Victorian times through the early part of the twentieth century (thanks in no small part to the Görlitz, a city of less than 100 000 at the easternmost border of Saxony with Poland has stood in for numerous other cities, because it was left nearly unscathed by the war and has seen few urban planners trying to rebuild the whole thing according to their vision since.
Conversely, filming in a story set Twenty Minutes In The Future will have its own problems because to make a location seem futuristic would require a lot of construction and visual effects anyway.